This specific feedback is a tricky thing to handle because a lot of Ret paladins are used to mashing buttons every GCD, and any time they aren’t in that state they are going to feel a lack of “rhythm” (as you put it). Yet if you look at rogues and Feral druids, they can’t hit a button every GCD because they don’t always have the energy to do so.

We don’t want classes / specs to use every GCD. We don’t think that’s good for the game, as I’ve mentioned before. (Casters do their waiting while casting rather than in between abilities.) The trick is to fill “enough” holes with something. For some players, especially some Ret players, that “enough” is going to feel weird for them unless it means every single hole. That’s not what we’re going for though. Wasting every other GCD is too extreme and isn’t what we’re going for either. (Source)