Force Bubble didn't seem that good because it seemed to be Anti-Tank because the tank could aggro, make a big ball, and if I pop Force bubble they get blown back
Admittedly, Force Bubble had limited utility in a lot of situations, and it's gigantic size also posed some problems. But, there were some instances in which it was useful... namely anytime you have an enemy, like a AV, who would basically ignore it because it resist Repel, but had minions that did not. It would then insure that you only had to deal with the AV. Unfortunately, since it was your attack, it would force the minions to all want to maim, kill and destroy the user.
But, even I, a staunch FF lover, thought that power should be re-thought a bit. At the least, it should have been made a bit smaller so that it could be more easily managed like those in Storm Summoning.