There has been a lot of feedback on this topic, but I think simply combining the armor into one is the most simple and effective solution. As it currently stands the most synergy you can get in a party... is every member with the exact same spec, and then all members with the same damage type.
I don't intentionally power game, but I'm so experienced with these sorts of games and just have fun optimizing and theorycrafting builds that I can't really help it. If something is suboptimal, I'll notice and can't ignore it. In divinity OS:1 I enjoyed a large variety of party comps and many could be viable. In OS:2 I'm having a lot of trouble with that. It's either all physical, or all mages. Even with mages, i'm finding it's best to have them all the same element like pyro / geo or aero / hydro. That way their surfaces dont' conflict and you can just turn the battlefield into a synergistic firing range.
Though, magic synergy is far less a problem than physical/magic synergy, being that there is NONE at all.
Beyond combining physical and magical armor there is a second solution, which is to make magic CC blocked by physical armor (some are, like impale) and make physical CC blocked by magic armor. This isn't as ideal since it FORCES a diverse party, but it's better than the current way of things that imo forces all the same damage type in a party.
though magic has the option of necromancy to deal physical damage and physical damage dealers have options to deplete magic armor as well. I think that both solutions are viable and would be most welcome.