It's about being effective and not simply "looking cool" ... how much can you laugh when you roflstomp everyone with your shitty transmog?
By wearing a very simple and basic transmog. Those pieces you find in 10-30ish areas. Nothing too bright. Muddy textures.
I managed to never be targeted this way as spriest and as mage now aswell. Everyone ignores me. Even my arcane mage who is mostly priority in RBGs. Nada.
It makes a psychological difference if you wear "cool" and uptodate tier gear or really unimpressive green unlisted transmogs. And ofc you dont jump around like a clown while having 'zerker buff...
Try it for yourself and be baffled...
PS: And ofc dont jump like an idiot when you pop your CDs... -_-