[Update]: Blizzard are creating and giving away a unique mount based on player votes!

In order to prevent players from combining multiple damage-increasing effects into a single button, Blizzard introduced a global cooldown (GCD) to most abilities. While this did indeed have the desired effect of reducing burst damage, it came at a heavy cost.

Since the affected abilities didn't change in any significant way, the players still had to go through exactly the same rotations as before, just with far more stop-gaps sprinkled throughout. So if you used an ability that increased your damage for 10 seconds, you would realistically only be able to use 9 of those seconds, and that number only went further down the more abilities you needed to chain. Not exactly ideal, I'm sure you'll agree.

Thankfully, after two years of complains and some half-measures here and there, Blizzard has now finally seen the light. As a part of the upcoming Shadowlands expansion, most abilities that fall under "burst cooldowns" will be going off the global cooldown and back to how they were before.

Best of all, Blizzard is looking to slowly transform these abilities from boring effects like "click button to receive 10% more damage" into more exciting ones like the Demon Hunter's Metamorphosis which functions as not only a damage buff, but also a mobility tool and stun. This is probably going to take a while to fully accomplish, but from a 'power fantasy' perspective, I'd say it's definitely worth the trouble!

You can read a little bit about Blizzard's reasoning, as well as check out which spells are being changed, over at the official forums.