I've also looked upon the splined adaptor as a fit and forget part. In what circumstances would it ever need to be removed?
Two possabilities I can think of:
Damage probably isn't very likely, but those sorts of split ring retainers do break, usually as a result of cack handed fitting or removal of the ring.
Or to change it for something else, there's three or four types of adapter, plus the threaded sprocket. Maybe you'll never have need to change what you have now, but who knows? Maybe a different chainset would benefit from a different chainline, or something completely different comes along.
I sent us down this spur, wondering if anyone else bothered, it wasn't a recommendation, I'm not going to disagree with anyone who says they don't touch it after fitting. I have the tool (I had two but gave one away) it adds 10 min or so to the annual service, and I like the idea that things designed to come apart are maintained to do so with ease.