Haslem absolutely should have his number retired by the Heat. I don't think it is even a question. 2nd in games and minutes, 8th in points, 1st on offensive, defensive, and total rebounds; 10th in blocks; 4th in WinShares: etc.
On top of thet he was the starting PF on 3 separate champions.
So by that logic, the Magic should retire Nick Anderson's number, too? 1st in games, 2nd in minutes, 5th in DRB, 3rd in ORB, 4th in TRB, 2nd in points, 5th in assists, 1st in steals, 2nd in win shares... 0 All Star appearences. He can join Shaq, Dwight Howard, Vucevic (who I don't think is deserving but has an even better resume than Anderson), Jameer Nelson (also shouldn't, but fits these criteria). And other must be arguable if those guys shouldn't even be a question.
Playing for a team for a long time means you'll rack up counting stats, but it doesn't automatically mean that you should get your number retired. It takes (or should take) more than that, especially for a franchise who has had legitimate success like the Heat.