I strongly dislike the artificial restrictions on which enemies can be damaged. I want to take my basic starter weapons into high level areas, in part because that's the only way to get some semblance of difficulty in the game. (See other feedback threads for a discussion on the broader lack of difficulty.) There's some whimsy in bringing a rusted sword and a letter opener to a high level area, then relying on tactics and skill to win anyway. Since low tier weapons can't do more than 1 damage to enemies with a gray health bar or a gray X for their level, that strategic play is effectively impossible.
To put it another way: let me nerf myself!