Look, I don't mean to be funny, but I'm getting a little tired of everyone talking negatively about sniper rifles... If I had to choose a class, they definitely wouldn't be my 'weapon of choice', but they're still solid weapons. They DO take a bit of skill to use effectively, and aren't ONLY used by trickshotters and quickscopers.
1. Sniping can be used tactically to cover teammates whilst they play the objective, or pick off opposing forces in non-objective based gamemodes, contributing to the win.
2. What's the big negative about quickscoping or no-scoping? It's just used as a quick last resort when enemies get too close (it's faster than reloading). It can also be used as a primary method of firing, as to some it's easier than 'hard scoping'. Also, if you came "up-close-and personal" with an enemy using any other weapon class, you would panic and try to kill the enemy using the quickest means possible. In MW2, this would've been 'Commando-Knifing', which was as equally annoying to most as sniping, dropshotting etc. are currently.
People are just going to try and pick faults with every CoD; it can't be helped, but neither can sniping - it's in the game for a reason, and is very effective when used correctly. To add, sniping will (about 90% of the time) always contain an element of camping, but this is expected as the player will make use of the sniper rifles' long range advantage, and spending less time in 'Close Quarters'.
In my opinion, trickshotting is probably the only factor of sniping that is deemed a negative. However, it shouldn't be complained about too much, as if the enemies are trickshotters, they are placed at a huge disadvantage. On the other hand, I understand that if you are unfortunate enough to have trickshotters on YOUR team, they will almost definitely damage the teams' chances of winning, making it very frustrating.
This is why sniping is looked down upon. It is made to look inferior in effectiveness by players who do not use sniping properly, and is being rapidly ruined- as is the reputation of Call of Duty as a whole.
(Trickshotting definitely isn't the sole reason for the downfall of CoD).
To conclude, I'd just like to reiterate that I do not snipe regularly (I'm more of an SMG kind of guy), but I do enjoy sniping from time-to-time. But I generally have quite an aggressive "play to win" play-style, and sniper rifles don't support this as well as SMGs or assault rifles. I hope I've changed your take on sniping slightly, and just remember: "Hate the player, not the game".