Djokovic is the greatest returner who has ever lived. He is far from boring and not arrogant at all. He along with Nadal and Federer are among the most gracious and humble champions ever. If you want arrogance, look to the Williams sisters who seldom praise their opponents.
Possibly you have forgotten Andre Agassi in offensive service return. I am not taking anything away from Djokovic’s tennis game, but he has never been an overwhelming crowd favorite and he has admitted just that, it has been his Achilles. Throughout his career he has had to beg for applause, and has made comments that he has never been given the respect Federer and Nadal have received, which has been his career quest.
Djokovic has become more popular because of his anti-vax stance.