The easiest thing would be to get rid of the tank controls - just have eight movement directions from WASD, and disable the bouncing off walls thing. And make it so that you can just walk into body segments to attach them, though the mouse option would still be there.
However, in essence, you ARE a literal tank, so tank controls do make a lot of sense. So I think it's probably better to keep the slow movement and reduce the difficulty on the enemies - lower their vision distance by a lot so you have time to prepare and not get ambushed by a bunch of enemies (currently they can see farther than the player can which is a bit ridiculous), and lower the amount of damage they deal to your segments.
Like, it depends on what game feel you want, I would say... do you want a fast-paced action dungeon crawler, or do you want a game where the player feels like a big, lumbering, nigh-unbeatable monster?