Way back in beta I'd suggested a BzR mechanic, basically BT reduced the CD of BzR by X seconds and it worked so that BzR lined up with every Colossus Smash. This worked at the time because we focused so much on CS, and could be forgiven for doing less outside of it. In a world without CS though, that doesn't really help.
Ultimately, I consider any BzR mechanic or stacking crit buff to be a half measure. It doesn't fix the full problem. Stacking crit works fine for Mages because if Fireball doesn't crit... they recast Fireball. There is no downtime.
Conversely it doens't work for Bloodthirst because it has a cooldown, and being locked out from actions for 4s+ isn't fun. Its a total design flaw. I've yet to meet a single person in this game who said "man Enhancement Shamans would be so much more fun if I only pressed Storm Strike once every 5 seconds and nothing else!" Or any such similar nonsense. Players like being engaged, they like pressing buttons. Sure it can be over done (cough:Gladiator90+APManyone?), but it isn't a whole lot to ask players to keep up with 40-70 APM.
When you think about it, it undermines the whole Haste idea too. Its another example of erratic, incoherent design. There is no point to shorten GCDs when you don't fill GCDs. Arms is a prime example. It sounds good but just doesn't work out in practice. It would be so much better to put things on a standard GCD so that you can more accurately measure APM and set a better tempo for the rotation.