I assume you have KZ3, trust me medic is OP.
A lmg that you can easily kill at any range, ability to revive others, a personal sentry drone that follows you around and stays even after death, and the ability to revive yourself, and when fighting the drone which acts as a sheild so you need to kill the sentry first most of the time before you can kill the medic, and while fighting multiple enimies inluding the sentry, its not your fault for not killing him while hes down, usaly there all medics so imagine nedding to kill 4 or 5 guys twice plus a sentry each. A team of medics is way over powerd.
I assume you don't have the game, your experience of gameplay is clearly outdated.
All guns except the shotgun can kill at any range.
Medics are one of the most underpopulated classes in the game at the moment.
And I don't know where you're getting the idea that the sentry needs to be killed first, they're weak as, and don't often kill you by themselves.
..Also, how is reviving OTHERS op? You know that's in Brink as well right?
EDIT: the sentry drone does NOT stay after death. It stays while you are in last stand. If you finish the medic, the bot explodes automatically.