There no reason gameplay wise why blizzard cannot start making Crowd Control spells share cool-downs.
For Example Shockwave and Stormbolt. Both spells could be a 30 second cool-down with Stormbolt being 4 second and 20 yards and Shockwave being 2 second and aoe?
Like i know some spells would need be modified but surely this is the best way to allow trash / group aoe in mythics whilst purning it from pvp?