Why are people getting on lebrons case for leaving?

look i dont like him as much as most of you do, but i see nothing wrong in him leaving, yes that one hour special was a jerk move on his part but thats not my case, my case is that people here are saying hes a sellout for leaving, well havent you noticed other greats have done it too, kareem, wilt? how about shaq he left a championship caliber team in orlando for a good but not great laker team at the time no body was on his case, i garuntee you all if kobe was a free agent 3 years ago he wouldve left the lakers no question, who wants to play with kwame brown, sure mj said he wouldnt play with magic and bird and vice versa but all 3 played with stacked teams why would they want to leave, bosh and lebron had every right to leave cleveland and toronto, hell i would be pissed that after 7 years my best sidekick was mo williams, so really apart from the one hour special why is it so bad he left cleveland?