I would fully support 2h giving parry strike-through. But the point of how it affects Slayer/choppa and wp/DoK doesn't take into consideration that every tank can go shield or 2h, WL 2h(or single for some weird reason) and that WE/WH are forced dual wield. If down the line, class changes are input to allow more alterations of how you equip, IE allowing for 2h or duel wield on more classes, then I think it would be more balanced.
And about the RP question, just cause an RP CAN be super tanky, doesn't mean that particular RP IS. Same goes for every class. It is dependant upon the particular build/player... Theory crafting is one thing, situational awareness is another.
Edit: Your point is still valid though. The dev team always needs to take player input with a large grain of salt.