Perhaps it’s simply a case of business realities.
Probably
Oh, I think we can take that as a 99% certainty. Here are just a few costs associated with such an efflorescence of models and fits as offered by Thorne while Andy Blance was their designer, all of which I knew about before I went to business school:
Cost of capital (interest, repayments of loans cutting into distributable profits) to finance so large a range, warehousing space built or rented, sales lost because a large range of sizes and fits and models must be compensated by reduced colour range which is arguably more important to the vast majority of bicycle purchasers, time to train customer-facing staff in so large and varied a range, multiplication of showroom fit-out of so many models meaning larger stocks of expensive parts. The absolutely brilliant 100 days free trial also brought costs to the vendor, as well as welcome buzz on the internet. We also saw some of the fits at the margins being offered well after the main body of the production was sold, often at bargain prices; these discounts are an additional cost of so large a range.
On the other hand, you might say that the two main ranges established Thorn with a bang as a premier manufacturer of touring bikes after making custom bikes ran into a brick wall of costs and Far Eastern competition, and very likely brazier staffing problems too. (A quarter century ago already, when I drew a design for a custom bike built of triangulated small tubes, I couldn't find anyone except art school welders and silversmiths-- Jesus help me! -- to braze it together for me.) Thorn wouldn't be THORN today without all that; it might not be more than a fringe curiosity, as so many of the once famous custom builders in Great Britain have become. Whichever way you choose to do it, it is expensive to establish a mainstream brand, and niche brands perversely cost more to establish.
There is a time to take such a risk, and pay its costs, and inevitably a time arrives for consolidation and rationalization.
***
It's worth saying that this is a standard business school (or at least good, meaning non-political, business school) applied micro-economics analysis: in short, a point well understood would arrive where the owner of the business would have to make some unavoidable hard choices.
Personally, I came to appreciate Thorn's exquisite care for the fit of their riders after Sheldon Brown drew my attention to it, and to Mr Blance's insistence on the best value, long-lasting component choices which would least often immobilize the tourist in some godawful place.* Getting on for twenty years later I see no reason to change my mind about either early impression.
*In Oz you get a choice between 'The Pub With No Beer' and 'The Fatal Wedding', the latter 114 stanzas that start, 'The Hearse Overturned At The Crossroads.' You shoulda stayed in Melbourne: at least there you can get a 'Floater' from the cart at the bottom of Spring Street, which is a meat pie in a bowl allegedly of pea soup, and the only danger is the tram lines bending your rims as it they cast you onto the tarmac.
