I still hope it's all just planned as a "has to overcome the nika influence" type of plot. Where Luffy is basically like he's on drugs - feeling free - and he needs to learn that too much freedom comes with a prize, cause his friends can actually die, if he's fooling around.
Gaban's shit talk gave me real hope tbh. G5 by itself is not really the problem, it can be incredible if used right, all the over the top gag shit is what's hella annoying.
I'm not even sure if he used haki against Imu. It's like Nika mode makes him moronic