It wasn't the hit detection as much as the way SRB2 plays. The thok forces you in a direction, making you a prime target if you're good enough to align your crosshair right. Tails is a target with Rail as it is, and Knuckles is really quite hard to sniper out.
You still miss a lot, but considering all the other weapons don't instantly hit, if they don't have Rail, they have no means to fight back, so you can fire at will, and there isn't anything they can do about it. Without the sniper sight it's more balanced because they can at least see the player sprite they're aiming at.
In other first person shooters, most all of the weapons shoot really fast bullets which hit instantaneously. Hence, a sniper weapon is still great, but you can still be hit by spray in your general direction, so while they're in a bad situation, they can still at least futilely fight back =P