You can a also play with a low AC if you want a better challenge.
When I'm playing a turn based game video game I want the game to challenge me... which is very different than challenging myself with stupid rules or self limitations because the game's is poorly balanced...
OPStuff-wise, AC is probably one of the last issues of the game... if it is one.
With all due respect, I think there is nothing "stupid" about self-limiting or adding extra rules to the ones that the game provides. For some games it would not make much sense I agree, but for an RPG it does, just like the official DND rules can be tweaked by a DM.
Tweak rules and not use some core mechanics of a game is very different. Keep in mind that this is a video game and our "DM" has already tweaked many things.
When you are playing DnD you are not limiting yourself because things are broken OP. When you are playing TT games you are using the rules the game allow and you're bot changing them "because".
Sure I may not have written "stupid" because everyone is free to play how he wants to... but I guess most players of turn based video games are looking for a challenge without having to not use this, this, this, this and this.
I'm not even talking about barrelmancy which is a "full play style"that require a lot of efforts.
But I won't ever be happy to die or feel challenged by the game if I choose to let my party die because I "don't want to use" a poorly balanced base mechanic of the game like throwing a potion...