I think it's intentional to not give you something like an indicator as to how close you are to get kicked for bad behaviour. If Trolls would know that, they would TK exactly until that threshold is reached. But the system needs to be more punishing indeed. Something like 3 TK's should definitly kick you out of the game (Mind, TK's that were forgiven do not count towards that) Also, like mentioned, the last TK that would kick you should fire afert a like 10 second delay, so the last victim can choose to forgive. And if you get kicked out of a game because of Teamkilling, you should not get any of the XP or Requisition you accumulated in that verry game. Otherwise Plasma-into-melee multikills would still be enough of an incentive to get kicked and drop into the same game again...
Ye can't get stuck in roight propa' if'n ye can't risk krumpin' anuvva' boy ta' krump dem oomies gud!
Random pubs are pretty bad about forgiving TKs, even when it is absolutely their fault. Meleeing vehicles, walking in front of you as you are firing or in front of a charged PC, and then they get upset when they die. If anything, it needs to be higher.
I am very much against this. If someone is doing it on purpose, then start a vote kick. The penalties for it are harsher than I think they should be as it is. e.g. plasmablob on a downed ally (who is very much by himself and in the process of being executed) -> no forgiveness -> Well I guess I should apologize for stopping you from being humiliated and providing meaning to your death.
We have successfully kicked Nightbringer or whatever his name is before. That's really the only time I remember bothering with it.