I attribute this phenomenon, at least as far as using words like super crazy, awesome, creepy,
hilarious, etc. to a general tolerance for exaggeration. Essentially, we have a tendency (at least in American English) to want to emphasize, but pretty soon it becomes the baseline, leading to something no longer just being "amazing" but super amazing.
My gf says that it's not just the tendency to exaggerate, but the expectation it puts on everyone. In other words, when some people say "that's amazing!" it forces us to say "that's really amazing!" even when we don't want to exaggerate, only to distinguish our genuine amazement from the hyper-used term.
My favorite quote regarding this phenomenon is along the lines of:
"If a Big Mac with everything on it is awesome, then how do we describe the Grand Canyon?"