In cataclysm, the game-play was a little more interesting in this way. FoF charges needed some management. Il, FFB and DF required all a FoF charges.
But the remove of Deep Freeze's damage, the switch to BF-FFB without FoF and the reduced proc rate to have more control have change this aspect.
I think the change to FFB was good but the remove of DF wasn't.
In PTR 5.2, it seem that they want FoF generation to come more from Proc. It's a good things to game-play but not enough alone.