Look at his record and then maybe you'll see why he's still around. Why would Real Madrid have came knocking if he was sub-standard? He's a brilliant manager.
He obviously has a a lot of ability in some areas.
But from the outside looking in, he seems incapable or too stubborn to address issues most people consider to have held the club back for years.
Given that and the lack of recent trophies, I agree questions must surely be asked.
No degree of past success should give someone endless time to get things right.
Having said that, it only makes sense to consider removing him if you feel there's someone who will come in and do a better job. I'm not sure it would be that easy.