Sigh @ this review. Don't worry, I'll be constructive in my criticism.
T'would appear to me that you just suck at Crysis. Or didn't put enough effort in trying to really dominate the game. The suit is critical; to say it could be left out with little effect on gameplay is clear evidence that you haven't grasped its versatility. If you're getting raped on the highest difficulty anytime you're out of cloak and having to rely on "sniping" everyone with your silenced machine gun then you're just doing it (very) wrong.
Once you become comfortable with controlling the suit while taking action you can do all the "cool stuff" you want at any difficulty level. You'll find if you press the action when you encounter large groups of NK you will succeed much better than if you hide behind bushes far away. You do realize that a silenced weapon does considerably less damage, especially the further away you are? It's much to your benefit to have your weapons un-silenced. And by press the action I mean you have to use all your tools to your advantage. Having the ability to smoothly and swiftly shift between all your suit mods as you need them, making it a seamless transition during combat is paramount to your success if you want to actually experience a challenge.
Crysis is like a realtime, action strategy game. Unfortunately you're not thinking about all the options available to you. Aside from objectives it is entirely non-linear. You go as fast or take as much time as you want and you can go anywhere you can jump or swim to. Assault any encounter from any angle using your fists, weapons, the environment; whatever you want. Most of which is destructible. Vehicles are also quite diverse. Speed them right into a KPA compound area, run over a few guys, hop out before it is too banged up and use the thing for cover. Or drive the sh*t right into one of those little machine gun nests, or into one of those sniper towers. They will crush or fall down killing the guy inside, rendering the machine gun useless.
You need to use your tools in an integrated manner like making sure to tag with your binoculars every target you can in an area and recognize the capability of your suit. You'll also discover that if you press the offense and not run scared on the defense that your enemy will react much more realistically and lethally (read: challenging). When you go get in some good CQB you'll appreciate the ability of the AI a lot more. Can't stress pressing the action enough, pressure them to run for cover.
Next time you're runnin' along with your cloak off and are spotted, before you become surrounded, drop prone and cloak. Tag one or two of them with your binoculars for your bearings and then sprint off to cover (tree, grass) and uncloak. When your energy is charged cloak around until you can get a shot at one of them, don't think, just go to strength mode (you'll hold the gun more steady, less kick and the shots are more powerful) and open fire on him and don't let go of the trigger till he's dead.
Then recloak (you fired while in strength so energy is still high) and run to a different position. Rinse, repeat. You can run circles around them.
Don't forget your grenades (3 types in the game) and your tranquilizer dart (Tactical Attachment that knocks a guy out for 60 seconds) and your grenade launcher attachment. Plenty of great opportunity to use all the tools at your disposal. Got a helicopter on your tail? Don't scramble for a rocket launcher if you ain't got one, bust out that machine gun, go to strength mode, shoot at the missiles hanging underneath its small side wings. They will explode damaging the engine.
I mean hell, you can even run up and grab a guy (if you sprint up in speed mode you will cause your enemy to flinch for a few seconds) by the neck and hold him out in front of you as a human shield. His buddies while shooting at you will blow his ass away, meanwhile you can still shoot whatever gun you have out in your right hand.
Final note. Yes, the storyline is whack and the last quarter of the game sucks, it becomes linear and you fight in a stupid, confusing alien place and then on an aircraft carrier, much lulz ensue. However, characters and the storyline and crap should take a backseat when reviewing a first-person shooter; it's about the gameplay. Which you'll find, if you give Crysis a real try and become better at it, it's gameplay is truly unique.
whew, now take what you've learned and get back on that horse