Marcelo is clearly not a starter, whether he leaves or not is up to him. Fans know it's about time.
Modric has started as often as Fede and has been less influential. Everyone and their mother knows he's been demoted to rotations as he should have been at least a year ago. Starting less when you've started everything and you've been irreplaceable means you're not a starter.
What indication was there of Kroos being pissed off?
Suarez is erratic in his reactions indicating he doesn't think. He plays and then regrets having not rested. Benzema on the other hand plays, doesn't question anything and whenever on a bad run and somebody questions whether he should be benched, he doesn't respond by getting pissed off, instead questions himself. Therefore manager feels obliged to help him and reassure him because otherwise the pussy loses confidence entirely and is useless for a season in a time where we need goals more than anything else.
And Suarez plays for NT while Benzema for thrown out for being a twat.
Again, basically everything's different between the two bags of seniors. Their responsibilities, personalities, circumstances, in some cases playing time, often times attitude to the youth. Age is the only remotely comparable thing.