I think we've already seen evidence of the backlash
@Padfoote. Look at the number of negative posts this thread has (mine included). Yes, I have downloaded curse to play ftb. I still feel railroaded into the use of it.
Having used the three major launchers at some point through out my minecraft career, by FAR the ftb launcher was the best. Curse is much more convoluted to use. For as bad as everyone on the team (that I've seen on this thread) has said it was... It was in actuality far more user friendly. And it did exactly what it was for.
Curse has to much other baggage on their launcher. They are trying to have their hands in to many realms. If they focused on one realm (re: battle.net, minecraft, and now wow) I doubt the backlash would be such as it is. Not to mention the unneeded features.
[Edit] Perhaps SepirothWS mentioned what I recall reading about back in the 2000's before MC even existed...
Maybe I'm old fashioned. But I want my gaming experience to be centered on the game. As it stands? I spend more time cursing the curse launcher and what it stands for than I do actually playing the game. Yes, this partnership started 2yrs ago, but now when it comes to being a partnership... Ftb and its users are losing. I worry what other unforeseen consequences there are. Up to and including the loss of the FTB brand.