Disclaimer - this isn't a proposition of changing anything, this is merely to spark the discussion about Jeff Kaplan's idea of hybrid tax and him being under the impression WoW was going to be a tabletop campaign or something.
In the past, Blizzard had a stance of "hybrid tax". If someone is unclear as to what that is - it's the idea that hybrid classes should do less damage to offset the utility they bring in various other areas. Like, a druid should do less damage by principle of having healing spells, buffs, CC and the ability to switch to a bear and maybe hold some adds on him for some time, something that a rogue cannot.
When it comes to vanilla, I have always disagreed with that principle for 2 reasons:
1. No class would ever switch between specs in the middle of an encounter, so having you have to specialize to do damage, or to tank or to heal shouldn't affect "class balance" or make you regret picking a pure dps class just because if you picked a druid you could've healed aswell.
2. Hybrids for some reason (in WoW) had a very finished and fully developed healing spec. Everyone always says they are jacks of all trades but masters of none, but it seems to me they have been pretty much masters of healing. So isn't it unfair that while their healing specs are properly polished and finished, their dps and tank specs were lackluster and useless?