Wait, are people saying magic is bad again? Guess I'll have to write a guide again and prove them wrong, I already sense so many powerful combinations coming out of magic schools, even excluding summoner.
As for the armor system, it's not the best sure, but it does have one advantage that I don't see many mention often, it's the opposite of rng, which was the reason it was implemented, which is why I believe the "return to saving throw", "percentile saving throw" was never even taken consideration because that goes against the initial philosophy. The armor system is to make it so when players die, they can't blame it on luck like xcom2, but simply accept the fact that they failed, and make it so that people don't need to reload because they failed a 99% stun, or simply, savescum. I appreciate how the game doesn't encourage savescum in any way.
The only problem with the armor system I see is the fact that it doesn't encourage having both physical and magic damage at the same time, but what people fail to realize is that, a lot of physical skills remove magic armor and schools like necro, poly, often scale int to deal physical damage, and the fact that some enemies have way higher type of one armor than another, for example, windego, her physical armor is like 24 while her magic armor is like 200, which encourages the player to use physical damage on her.
tldr I think the armor system is fine, and I wouldn't come up with a better solution and I haven't seen anyone come up with any.