Why do people hate on snipers?

I really dont understand why people hate on snipers so much? It is the hardest gun to use in the game and when people get good at it they make it look easy like these to clips I found.


http://www.youtube.com/watch?v=ABylzTVp0w0



http://www.youtube.com/watch?v=hFAEeq7XhlM


the editing is amazing also