Blue
Ravenous Bugblatter Beast of Traal
Except that you addressed one point while ignoring the context that it was in. Which is that when you start wanting to introduce magic and materials and such you end up with a huge number of armors.Though that is true in 5e, that does not need to be true. Yes, in 5e once you get Studded Leather as a Rogue, there is no longer any reason to have Leather Armor, and the same thing applies to Chain Mail with Plate Armor, and Scale Mail with Half-Plate.
However, that is only due to the fact that 5e's armor system is dumbed down and simplified to the point where any choice besides the obviously optimal one is a wrong choice. If the system were to be changed to there being a type of light armor that was more expensive than Studded Leather, possibly 100 gp, which would give you an AC of 13 + your Dexterity modifier, with a maximum bonus of +4, then in certain circumstances it would be better to take Studded Leather than this hypothetical armor.
And, that's just one example they could do similar things for a variety of new light and medium armors (possibly a heavy armor that is 17 + Dex mod., maximum of +1), and other similar ways of keeping armor simple while also having the choice matter.
And your example of making it more fiddly (introducing a new max dex besides +2) makes it even more of a pain. How does introducing an armor that in exceedingly limited circumstances it is better improve the game, lower the barrier of play to new players, make sure that players actually can use and enjoy new magic items instead of them being potentially a bad choice, and just improve fun for everyone, not just those with the system mastery to compare multiple dimensions of change across the equipment list to figure out what's best right now. In an edition that's worked hard to get off the gear windmill.