A game with instant recast timers (ie, no global) would be a nightmare for players without stellar ping. Did you even Blade and Soul? Animation canceling made that game brainless AF; just smash your buttons in arena and hope the other guy lives in Australia.

That said, 2.5 seconds is a hyperbolic eternity and I'd really like to see the GCD sped up a bit. Yes, I'm aware MNK and NIN have shorter ones - 2 seconds, thereabouts; still double the time of any non-DK class in WoW. Devs, please stop assuming we're all controller users or keyboard turners with sausage hands and speed up the gameplay a little, thanks. You can thank me for your players not quitting before they reach level 30 later.