So if Kobe was still alive, the Mavs players could still wear 24? If so, that pretty much confirms it's just a reaction to his untimely death. It has to do with that way more than anything Kobe did on the court, imo.
It's the first time I've ever seen a team retire the number of another player who never played for them (not counting Gretzky's or any other league-wide # retirement).
But 8, his other number, is still available. He did a lot wearing 8 as well. Cuban forgot to retire both numbers.
It would get complicated for some teams to be that hero and honor someone like that, if said number is already retired by one of their own players. If something happened to Larry Bird, what if another team already retired 33?