I agree with you - no way does the A10 look like an upgrade.
If anyone reading this does not see it as an upgrade, that's fine and a personal choice of judgement and that's great. However... it should be seen as an acceptable "lateral move".
I used to play a LOT of disc golf. Guys would go out with expensive discs or rare discs or favorite discs and really, REALLY bemoan when they got lost or thrown into water. Over the years, I realized two things in succession. First, that if you didn't want the disc to get lost ... don't throw it or be more careful. Secondly (and more importantly), the game has grown so much that manufacturers sell discs on the retail market that do nearly the same thing - that dinosaur can be replaced by something very similar.
What I am saying is, you can baby your equipment all you want to, but unless you have a backup - at some point, as a consumer - you have to be willing to make a lateral move when your equipment becomes dated or inoperable. This is tech in the 21st century.
I have an M10 and an A10. If my M10 fails, I'm not going to eBay for another. I am going to embrace the fact that B and H sells A10s. They probably used to sell M10s. Now they sell A10s. This is both to the advantage of the consumer and the march of time.
Personally, just my own opinion, I think nostalgia is for the weak and shows an inability to reasonably compromise/be open to the present moment. Eye of the beholder, for sure, but, like, live for today maaaaaan.