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My understanding is that drop handlebars are required in races for safety reasons (they give a flatter surface for other riders to hit) - if flats were allowed I wonder if riders would change to them?
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I used to hate drop bars, used the drops maybe 5 percent of the time.

Then I lost about 15 percent of my body weight, most of that was in the middle.  A diagnosis for diabetes gave me the incentive to lose weight.  And after the weight lost I felt much more comfortable leaning further forward.  Now use the drops maybe one third of the time.

Yes, I agree, you want a setup you are comfortable with. In my case what I was most comfortable with changed in part due to weight loss.

I have flat bars on my errand bike.  That is the bike I use for short distances around town.  It is the bike I use most often, but each time I use it, it is only for a few miles.  Thus, I regularly use a bike with flat bars too.  I have no desire to change the bars on that bike, the bars on that bike work great for the purpose of the bike.

A friend of mine that I have done several tours with slowly shifted from drop bars to bars that I think are called bull horns, first photo taken in 2017.  He is my height but weighs about 50 pounds more than I do.

And second photo was taken in 2023, different bike and now he had flat bars with some bar ends that extend forwards.

Third photo, both of our bikes on that 2023 tour, it is easier to see his handlebar setup in that photo. 

My bike in that third photo is my titanium touring bike, that is not a good photo to see my handlebars, so I added a fourth photo that shows my handlebars better on that same trip.

Regarding your comment on racers, from what I have seen on racing bikes, their bars are often narrower than most people want.  I suspect that is to make them slightly more aerodynamic?  I have heard that racers try to even bend their legs slightly inward so their knees are closer to the top tube for aerodynamics.  Thus, I can't possibly imagine that they would switch to flat bars.

We all like different riding positions and it is impossible to really say that flats are ‘better’ or worse than drops - but I personally find that flats have more advantages.

I bought an alloy / carbon bike earlier this year.   About 20 years old, one owner from new, with drops.  He had obviously been happy with the drops but I was not.
- I could not find a comfortable hand position where I was near the brake and gear controls
- when I tried using the brakes from the hoods I could not get a good pull on them, so I would have to then move my hands down the ‘bars in order to brake….not good in an emergency.
- aerodynamics overall did not feel better….except when head down with my hands on the lowest part of the handlebars, where I quickly became uncomfortable.

So I converted it to ‘straight’ bars (Thorn bars that had about a 5 degree sweepback and which were reduced in width and fitted fairly low.  With ego type grips and stubby bar ends.  The stubby bar ends give me a very similar riding position to riding on the hoods of drops but with thumby shifters and flat handlebar brake levers my hands are close to the controls...and the brakes now work much, much better!  Hydraulic brakes on drops may work fine as little hand pressure is needed but the cantis on this bike needed the pull available from flat handlebar levers to make them work.

The previous owner of the bike was not impressed by my conversion but it worked for me.  It made the bike more comfortable, safer to ride and I feel I only lost out a little to the aerodynamics of the drop handlebars when they were used in their lowest position.

My understanding is that drop handlebars are required in races for safety reasons (they give a flatter surface for other riders to hit) - if flats were allowed I wonder if riders would change to them?

So in summary to the OP - if your bike has flat bars set up correctly, you may be best sticking with them!
And there are a lot of different ‘flat’ handlebars to try - I have narrow almost straight bars on this bike, wider almost straight bars on another and Thorn Touring bars with much more sweepback on my Raven.

My size 580L Mk 2 Mercury had a straight bar setup when new. The second owner converted it to drop bar which is how I bought it.  The original Thorn flat track bar and V brake levers were included in  the sale. I’d been accustomed to riding a straight bar Mk2 Nomad for the previous 9 years and wasn’t intending to buy a drop bar version but gave the drop bar setup on the Mercury a trial for a few hundred miles. I eventually decided to emulate the Nomad and convert the Mercury back to straight bar using the Thorn flat track bars and V brake levers included in the sale, mainly because,
1. Even with the 80mm stem (3cm shorter than the stem on the straight bar) I felt rather stretched in the riding position. I’m 5ft 11in but for my height I have an exceptionally long barefoot inside leg measurement (35in (89cm)) so a shorter than normal upper body.
2. Not relevant to the Sherpa but the Rohloff twist shifter on the drop bar conversion was placed on a short Thorn accessory  T-bar fitted to the fork steerer column below the handlebar stem. I feel safer having the Rohloff twist shifter closer to hand on straight bars within easy reach for rapid shifting without having to take my hand off the handlebars.

For information,
the 580L Mercury frame has a 600mm virtual top tube (I could be wrong but I think that’s measured as a horizontal line from centre of head tube/top tube junction to centre of seat tube). The 580S (short top tube) frame has a 575mm virtual top tube.
The drop bar conversion had an 80mm stem and my preferred  straight bar setup uses a 110mm stem.
In my case, if I wanted a drop bar Mercury I’d definitely choose the size 580S for a more comfortable riding position.

The Washington Post, in its obituary, quoted someone unnamed describing David E H Jones as the ’court jester in the palace of science’. That’s a witty description, but not fair, not exhaustive, not even comprehensive. David Jones did a lot of innovative thinking and writing for which other men took patents and even Nobel Prizes. An example is 3D printing, which Dr Jones laid out in New Scientist in 1974, 11 years before Chuck Hull ‘invented’ the process in 1984.

 He was also a prime practical prankster, the inventor of fake but plausible perpetual motion machines, one of which is in the Technisches Museum Wien (Vienna). On the other hand, I can offhand, without blinking again, name three prominent scientists that I have known who would have given their eye-teeth to have NASA carry their chemical garden into space, as they did for Dr Jones.

But, arguably, Dr Jones’ most important work for the future of the world, was proving that a bicycle with a reversed fork is stable.

That in the process Dr Jones incidentally killed the mistaken belief that some mysterious gyroscopic force was involved in bicycles staying upright, is a bonus but not all that important.

Bad thinking on that subject had already resurrected itself after Francis Whipple of Cambridge University in 1899 proved conclusively in the rigorous mathematics of his algorithm now known as the ‘Whipple Model’ that a riderless bicycle is stable.

And bad gyroscopic claims will resurrect themselves after Jones — probably about now, as fifty to sixty years seems about a Kondratieff Cycle for delusions of gyroscopes. Watch this space.

Here’s the bibliographic entry including a link for the article:
Jones, David E. H. (1970). "The stability of the bicycle" (PDF). Physics Today. 23 (4): 34–40.

The notation resolves to Physics Today, April 1970,  pages 34-40. If the link above doesn’t work for you, here’s the link full out:
https://www.phys.lsu.edu/faculty/gonzalez/Teaching/Phys7221/vol59no9p51_56.pdf

There’s also a YouTube video about Jones and bicycle stability:
https://youtu.be/J5ICTbqKoEI?si=n5cQhf_KXDav0e9n

Here’s Dr Jones' brief biography at Wikipedia, coming with the usual warning about Wikipedia being a lowest common denominator source:
https://en.wikipedia.org/wiki/David_E._H._Jones

Hat tip to Danneaux, the confidant of AI, for the knowledge, the link, and a giggle besides.

Interesting photos there. Thanks for sharing. A crude measure I know, but looking at the guy's height I'm wondering if he has his saddle too high; with all the knock-on effects that can lead to re stem length, drops or straights? Guess we're all on that continuum at times. I use a shorter stem to the one I had fitted originally; just more comfortable. I've stayed with my expedition bars and ergon gp5s for the same reason. Interestingly I was originally looking at a 565L Nomad Mk2 but ended up with a 595L instead.

PS Hope the guy tensioned/changed his chain. Looks a bit slack to me! ((I've just replaced mine, along with a new 36T chain ring. I still dislike fitting a new chain though.)