I actually think the Showtime Era jerseys are the best as opposed to the 70's era that are posted in the OP. The inverse colors on the numbers and the tri color neck/armholes work better than the 5 ring ones on the 70's era ones.
As for most of the jerseys in this post, I think nostalgia is a big reason why people are ranking older jerseys, specifically those hideous 90's jerseys, in such high regard. Those jerseys LOOK like the 90's in general(bad color combos and giant caricature logos on them) and haven't aged well outside of being "retro."
As for why the NBA changes jerseys more often, I think there are a couple of answers, the biggest being money. Unlike the other sports, the NBA uniform lends itself to a lot more creativity from a design standpoint. Because of this jerseys seem to be more of a fashion item than the other sports (stars being more known probably helps here too).
The other reason I believe they change a lot is because a lot of teams haven't found THE look yet. The ones that have found it haven't changed really. The Spurs, Bulls, Celtics, Lakers, Heat, Knicks, Blazers all have timeless looks that haven't changed much. Every other team either got hit HARD by the 90's/00's craze and had to find their way back (Warriors, Bucks, Jazz, Hawks, Sixers, Nuggets, Rockets, Suns), are just too young, or without much successful history to identify with so they keep trying to find the look that'll stick (Kings, Nets, Grizzlies, Raptors, Hornets, NO franchise, Timberwolves, Thunder, Wizards, Magic, Mavericks, Clippers, Pacers)