Don't it only count as a TK if the player doesn't forgive you?

I disagree on this entirely. Killing someone whether they're downed or not is still a teamkill.

Wait for forgiveness and resume your high-explosive massacre.

This is very very un angry of you.

Where is Angry Marine and what have you done with him?

Maybe add a little math for a distance to nearest player? For example if you are throwing a kannon ball at a motherf and a guy happened to die near the motherf, is not your fault if he (completely) dies

Okay, let me put it this way:
STOP KILLING YOUR FUCKING TEAMMATES YOU EXPLOSIVES-CHUCKING HALF-WIT.

I DON'T GIVE A SHIT IF THEY'RE BLEEDING THEIR TREACHEROUS LIFE AWAY ON THE GROUND, WHEN HAS THAT EVER STOPPED THEM FROM GETTING BACK UP? ONE FUCKING APOTHECARY NEEDLE AND THEY'RE BACK IN THE GAME LIKE NOTHING HAPPENED.

IF THEY'RE STILL BREATHING, THEY'RE STILL ALIVE. ENDING THAT MAKES YOU A GOOD FOR NOTHING, PIECE OF SHIT TEAMKILLER. CHECK YOUR FUCKING AIM NEXT TIME OR DON'T USE THE GOD DAMN WEAPON AT ALL IF YOU CAN'T FIRE IT WITHOUT CAUSING DAMAGE TO YOUR OWN ALLIES, YOU STUPID CUNT.

Unless you're taking issue with the amount of experience you (don't) get... the issue at hand here is more the forgiveness system, I think.

If you gun down an enemy and accidentally TK a downed ally, that ally has zero reason to not forgive you since he was dead either way. If he doesn't forgive you, he either doesn't know how to, is too lazy, or is a salty fuck who doesn't forgive people for any reason.

The whole "hold E" thing is a very minor inconvenience. I imagine some players don't bother just because of sheer laziness. Considering how low the TTK is and how often friendly fire happens, you have to hold that E button a whole fucking lot.

I find myself forgiving around half my team kills. A lot of them are really stupid though and I refuse to forgive someone who makes a really idiotic decision... even if the system is there to punish deliberate TK'ers rather than satisfying personal vendettas. I like to use it as a deterrent to players who don't pay any mind to allies.

Why is team damage even in the game?

Because if team damage was completely turned off melee actually would be pretty much 100% dead save for the few people who just do it "for the feelz".

If I'm playing melee I want to be able to jump off my teammates back for some sweet aerial attacks!

Also, I can agree with the OP.