So my suggestion would be to give heavy and possibly medium armor an armor bar that depletes by taking damag
Edit: Basically the same as in Divinity OS2 but whith damage negation (Some heavy armor: Physical: 40%/20HP Magical/Hazards: 15%/15HP) and AC. For heavy armor to not get AC/evasion bonus from dex makes perfect sense I think.
Oh, no. Fuck, no. Please, God, no. Please.
Now, putting aside the fact that this a licensed game based on a well-established system and it should NOT be up to the developers to change it at will...
There's also the fact that if we are going to revamp damage mitigation in any other way, you chose what's arguably the worst reference possible out there.
I do agree that D&D 5th edition is not exactly exceptional in that area, either, but if changes were going to be made, there are better alternatives in spades.