it adds another layer of things you need to think about when you're playing the game. if spell reflect requires defensive stance and you jump into and out of dstance for something via a macro and you're on the stance GCD when you need to reflect a spell, that's gameplay decision making. I'm not saying stances are the most interesting gameplay ever, but you can't make everything as interesting as everything else. it just doesn't work like that.
It might be really annoying or something you don't care about doing, but there's a reason blizzard gives us buffs we need to keep up or stupid filler talents like 90 mage talents. 90 mage talents are really stupid and annoying, but mages would be too strong if they took the talents out and just gave them the damage passively. So you can choose between having annoying mechanics to deal with and be rewarded with more damage/utility/healing/survivability, or you can have arms warrior rotation that has very little you can do to excel and differentiate yourself.