Lol I play GTA online all the time, people abuse the hell out of passive mode. Follow you in a jet and wait til you're not paying attention, come out of passive, bomb the crap out of you, go back into passive. This is a bad idea for ESO honestly.
I am familiar with GTA's passive mode and its immersion breaking BS and a constant reminder of how it's not a real MMORPG.
ESO don't need to learn anything from gtao (quite the opposite)
And furthermore this idea is horrible.