I think it's just the comparison, whether fair or not, that Hansbrough is in the same league as Jordan and Worthy. Different styles and times of course so you can't/shouldn't really compare the two.
But when you compare anyone to MJ it's already kinda unfair. I could see why some folks wouldn't see how retiring Hansbrough's jersey makes sense.
Those are people who do not understand college and the NBA are different. Jordan was great in college but he wasn't the greatest, Worthy was a better college player than he was and Tyler has been as good of a college player as those guys and if he stays his Sr. year(something those 2 did not do) then he will pass them.