People are forgetting that not all have good eyesight. I have very good eyesight, and I can have trouble spotting enemies when they run behind bushes (the colours blend very well into each other). Using VATS will let you spot them, even with poor eyesight. It is also good for those who have trouble with fps in general.
Also, I don't view it as a cheat. It is just a form of bullet-time mechanic in my view, altho in the earlier games, it was needed (turn based combat) I use it occasionally, like when you are swarmed by bugs (there are several locations where you can encounter 6+ assorted flying things). Since the game calculates spread, even if your aim is dead on, you might still miss. So taking some high %'s when swarmed can be better in the long run.
Lastly, it is a single player game, as pointed out a lot in this thread. So who cares what people do in their game.