Anything a sniper can do can be done better at the front with an assault rifle. Sniping is for carebears, really. Shooting at people that usually is unable to shoot back, either because of range, stealth or because the guy you're shooting at is busy with doing something more important than you are.
This is more true in games where you can frag someone with just one shot to the torso, and not only to the head.
One class that is extremely rare is the 'marksman' class, and I'd like to see more of it. But of course, it's much harder then sniping since you will be closer to the enemy and can be shot back at.
And what's with the argument that 'sniping is hard'? You should try the front, it's MUCH harder.