On Heroic Strike being on the GCD:
I don't think it was ever on the GCD besides Cata Beta. HS used to be On Next Swing, which made faster weapons (1.5 speed) much better for tanking than slower weapons (2.6 speed) as it's almost twice as many HS's, meaning twice as much threat from it (which it was a pretty good source of threat in WotLK at least).
It is now on it's own shared CD with Cleave, and off the GCD. Inner Rage reduces it from 3 seconds to 1.5 seconds.