Now, I know what you're thinking already. "Isn't the Nanosuit pretty OP'd as it is?" Yep, and that's my point. The Nanosuit's purpose, gameplay wise, is solely to make you feel EMPOWERED.
Let's take a look at Crysis 2. I saw two annoying problems with the combat in that game.
1. You're too slow when sprinting and even walking. Now, I understand that, canonically speaking, Alcatraz's body was supposed to be completely wrecked. And you know what? That's fine. Just don't carry that over into the gameplay. And don't tell me they couldn't have done it without it clashing with the story. They could have just said, "The Nanosuit 2 is just that powerful." Seriously. That's all they would have to say and it would be just as legit.
2. Some sort of way to make it much easier to aim at targets. I would suggest some sort of bullet time feature or even an aimbot if Crytek really can't be arsed to put it in. (I should add that I am talking about this addition strictly with the campaign in mind. Obviously, this ability won't be in multiplayer.)
EXTRA: Make grabbing and manipulating objects more streamlined. Also, same thing with enemies. And turn down the energy consumption rate to throw/melee something at max power FFS! Basically, make any interaction a viable option in combat instead of a gimmick.
And that's it really. Now, obviously, a lot of this isn't necessary at all, gameplay wise. But I feel that these features would GREATLY benefit this game.
For a good idea of what I was thinking of, this guy has made a mod that changes almost everything I had a problem with in Crysis 2 and then some. Only thing that was needed was some sort of bullet time.
http://www.crydev.net/viewtopic.php?f=308&t=72955