A “The More You Know” moment from Ghostcrawler:
@theonerayman Our vision for rogues is not to have enough energy to fill every GCD. That makes energy not a thing.—
Greg Street (@Ghostcrawler) February 16, 2013
Obviously, this is an oversimplified answer in response to an over-the-top question: I hope that few, if any, reasonable players think that rogue design should revolve always having a button to hit after every global cooldown. In addition, the loudest and most numerous complaints about rogue “slowness” took place 1) early in the expansion and 2) particularly for Assassination rogues, whose main combo point builder (Mutilate) costs a whole mess of energy, meaning a fair amount of wait time between button mashes (and even more wait time if you don’t use Rupture to increase the chance of free energy procs via Venemous Wounds).
As Mists progresses and our gear gets ever-more haste on it — and as players simply get used to rogue gameplay in this expansion — fewer and fewer folks appear to be complaining publicly about energy regen issues. It’s likely this will continue to fade away — until the next expansion begins, at least. :)