Why can't we have both?
The entire premise of this thread is silly. Singer has already said before that Quicksilver was one character he's been wanting to work with. Heck, the character was originally in First Class but then was dropped. Not to mention, we've gotten word that QS plays into the character drama of DOFP.
The idea that they placed him in DOFP at the last minute to piss off Marvel is fanboy wank in order to stoke the flames between studios.
We've seriously turned into 13 year old girls fighting over which boy band is better. And all over what character? Quicksilver?