Have any of you armour haters played mass effect? It's the same deal. Maintaining your shields or armour whilst disabling the enemies is a core part of the game. Dos2 is the same and I'm not sure people have figured that out. Maintaining armour is core to the game and without it you get rocked hard.
Without going into too much detail (I'm at work), the offensive capabilities of magic and physical attacks differ. Magic handles aoe better, physical is more single target. Similarly, warrior armour has more physical armour, mage armour has more magical armour. Warriors beat on mages, mages beat on warriors.
There's a dynamic there and the game is built around that. It's not a case of me imposing my opinion, it's how the game is built and you're either for it or against it.
Additionally, I don't recognise all those points as being valid or true counter points. Not to say there aren't foibles, but just because you say them doesn't make them true.
1. All physical teams are better. There is no "magic is better at AoE" and "physical is better at single target" for the majority of the encounters. Physical AoE actually outright kills, while magical AoE suffers penalties from resist types and doesn't actually excel unless you have a minimum of three enemies clumped together (which is rare actually).
2. Mass Effect? LOL. Mass Effect 2 was absolutely awful if you wanted to play as an Adept, and it was the worst change from the first game that
did not have the double and triple layers of "health" that prevented your manipulation of the enemies. At least in that game though you had Warp and Warp explosions to quickly strip armor. There's nothing comparable to that in this game, especially with the high cooldowns.
3. Split teams in this game are bad. You can finish Classic easily enough with one, but you'll have a hell of a time in Tactician, and either going all physical or all magical is going to work out the best; with physical being the superior choice.
But what would I do anyway is change the itemization system in not allowing both types of armor on the same items - you should choose one to specialize in. If you want to wear both warrior armor (with physical resistance) and mage-relevant armor (with magical resistance) you can but you will be much weaker because of that. Versatility should have a big drawback.
Have you actually seen mid-game armor types? Because that's kinda how it already is.
Strength-based armors give a LOT of Physical Armor and a tiny amount of Magical Armor. Intelligence-based armors give a LOT of Magical armor and a tiny amount of Physical Armor. Finesse-based armors give a moderate amount of Physical armor and a lesser amount of Magical armor.
You don't get both unless you split your attribute points between STR and INT, which has a drawback of wasting attribute points.
Not really an issue late game. The highest of any stat you need is 14 for gear, and you'll cap your primary stat long before end game. After that, the only thing really left is MEM (not really needed for most builds) and WIT (not really needed other than for Crit oriented builds). Sparing 1-4 points to wear non primary stat gear isn't a drawback. The main drawback is if that gear doesn't actually have enough extra stats or skills to really warrant using it for the armor bonuses alone. CON is useful if you want a shield, but that's all it's good for, and you'll still have a surplus of stat points near the end. Prior to that point it actually doesn't really matter all that much anyway. It doesn't matter until Act 4 when inflation gets out of hand.