Because he walks around like an emo teenager in matches, complains, sulks, and goes down at the slightest contact. Morata's problems are not to do with talent but with attitude, and attitude is what makes a player more likeable or dislikeable imo. His "the world is against me" idea is annoying too, after his first stint he said the club was playing Mandzukic over him because he was only on loan while Juve owned Mandzukic outright. No self awareness to see how much better Mandzukic was.