I think the Melo hate or dislike comes from his max contract. There might others reasons too, but the thing that I might get caught up in in not being satisfied with Melo's performances is his contract.
Let's chop a few million off his contract now. He was last season's scoring champion, was a big part in the 54 win season, was a big part of getting the Knicks to game 6 of the second round of the Playoffs, and this season he stepped up big time in rebounding.
Is he a ballhog? No. Is there times where he should have passed? Yes. Al Harrington was a ballhog, and being with D'Antoni didn't help, much like Woodson and J.R. is bad (much worse than D'Antoni and Harrington, D'Antoni loved the three ball way too much and didn't seem to be biased towards Harrington). You know why people don't/didn't bring Harrington up as much as Melo? 'Cause Melo is a max contract player who is labeled a lot as a superstar. Forget the max contract, forget the superstar label, what he is is an exceptional player.
Melo also plays hurt a lot. I know it's easy for us, including myself, to look past at, because we see better players play better even while hurting, but it's not fair to compare Melo to others players. Melo is an exceptional player regardless, on a team that has lost a lot of key players from last season, J.R. has regressed massively for whatever reason, and Woodson is a terrible coach.
Melo isn't perfect, he has flaws which holds him back as being a true max contract player, but he's an exceptional NBA player.
The team has played a lot better since the little break, and if it continues, Melo could get a chance to get a lot of deserved praise since he will be getting a lot more help from his teammates.