I've bought the game yesterday and played only for 5 hours, but I've already had several cases when sway messed up my shots when I tried to peek on the enemy. Suppression makes it even worse. In fact, probably worse than in Bf3.
I don't know the intentions of adding it into the game, but I say that it negatively affects the gameplay of both passive and aggressive players however aggressive ones are affected the most because it is a lot harder to stabilize your gun when you are in motion.
Regarding suppression, I think that the game doesn't need it whatsoever. Bullets are already scary enough because in Insurgency you die after just 2 or 3 hits on you, unlike Bf3 where it takes 5, 6 or even 7 bullets to kill somebody at range.