RadmanmanaIt's too good to not run to mid. Which means you actually end up making the meta worse.
Can't you say the same about every other unlock or class that is run to mid in 6v6? Specifically the medigun.
Well, first, you have to clarify your question, because now you're questioning the whole format of 6v6 vs. the impact of an unlock (EDIT: this is a whole different discussion and it doesn't really fit in this thread).
Let's not forget that besides its effectiveness on midfights (and pretty incredible dominance on KOTH IMO), there are other problems with the QF too, especially being able to cap while using the QF uber (whereas the medigun ubered medic and ubered targets don't contribute to capping), as well as the self-healing while using a Quick-Fix uber (remember when clockwork ran sniper for half the game on gully? S14 LAN never forget). It's incredibly too good for midfights and is still a little too good for other fights (partially because of the fast healing, partially because of the speedy uber building). This means that you have to run QF to be on even footing, because ubers are practically useless against a QF. The only other play is to use kritz, and while it's perfectly fine to have kritz plays, the way it's used to counter QF (which is, basically, build kritz the whole time while just stalemating as much as you can, because overextending into a QF hold means death), promotes almost only 1 playstyle (incredibly passive).
I hope that is sufficient enough reasoning to point out why the QF is not a good change in the meta. If I'm wrong on something, please correct me; but I believe I have all my facts and mental probabilities straight. I'm all for having more unlocks, but everything should be looked at with a careful eye, and it's my firm belief that the QF as it is right now is not good for the meta.