I remember when I used to like this game. But now 3 quaters of the weapons aren't used, Because everyone constantly uses the most annoying ones:
Deagle
AWP
M4A1
CV-47
CS doesn't do weapons the way a lot of game do them. Take Battlefield or CoD for example, every gun is more or less as viable as the next one. The nature of CS however with its economy system means that for there be to times when each team is weak mean that certain guns need to be outright better or worse then the others. It's for this reason that the Famas is worse than the M4, that the scout/SG (depending on the game) is worse than the AWP, and a multitude of other balance decisions. Being that the M4, AK, and AWP are the best all-purpose guns in the game, it would also follow that people would take the most time to get good with them. They aren't annoying weapons as much as they are well practiced weapons.