It's because of all the black people. 
I know this is tongue in cheek, but to some extent I think this is an element at play.
There's a lot of coded language that gets used by hockey folks (e.g. Felger) talking in favor of hockey and deriding the NBA and its players.
Hockey players are "hard workers" with "good character" and "just play the right way" etc etc.
NBA players are "entitled," "primadonnas," "divas," "thugs" etc.
This despite the fact that a lot of players in the NHL actually act like thugs on the ice and serve no purpose for their teams other than to start fights with the opposing team.
Not to mention that to speak generally of NBA players, many of whom have worked extremely hard to rise out of destitution to become professional athletes, as lazy or entitled, is ludicrous.
another facet of this which gets under-appreciated is that the NBA just flat out has way more stars than the NHL. and it's cosmetic, it's not just the style of play in the sport.
think about it, in the NHL, players have helmets/masks on, and guys are constantly going in and out on shifts.
it's hard to be a "diva" when only the best-educated fans can immediately recognize you if you play on any other team than the home team.
the NBA, on the other hand, has no helmets; their uniforms that cover only half the body; there are big, easily-noticed differences in skin tone, height, and body type. you also have cameras literally right on the court giving constant close-ups of their faces, especially during free-throws etc.
so the NBA is inherently more star-friendly, and i think NBA haters need to get over it, it's a strength of that league, not a weakness.