They change to completely nullify magic damage including debuff/buff to remove. What I propose is something like fixed magic damage reduction and the chance of buff/debuff
Even I don't like the effect of gtb, making new physical version of gtb I can't agree.
You missed my sarcasm. My point was, if there's a magic nullification effect and people don't think it's overpowered, then lets see how they feel when their physical class is suddenly made useless. Then they'd be suggesting its change, just like the magic users (and those who want actual balance) suggest gtb's change.
The pro-GTB people are basically just "its fine if it helps me but not thee".
In reality, so that GTB doesn't make maya seem useless or second rate (because, who really wants to take 50% damage when you can just nullify it completely?), GTB should offer something like a set amount of mdef instead with a low chance to proc 100% spell immunity. If it was a timed spell immunity, it would make it more like SW/Pneuma/Kyrie which do not have an infinite duration.