Yes, you can remove it and the car will be fine. You can also remove the oil fill cap, grab the tower that is under it, pull it out (with some work) and just screw the cap back into the valve cover so it looks like a normal engine.
Engine covers are just the style now. It's been going that way since the euro cars started doing it a few years ago. They say it keeps the engine cleaner. I have never read anything saying it's done to insulate the motor.
OK, i was searching the forums on this subject a bit last night, and somebody said that the paint on the hood above the engine may suffer from the engine heat if the plastic thing is removed. Any thoughts on that one ?