The only reason I can see for redshirting (other than the player wanting one) is if a player still needs development and is buried behind others, particularly upperclassmen. A guy like Moss a couple of years ago made sense, since he wasn't at a position of need and seems to have a decently high ceiling. Olaseni would have made sense his FR year.
In both cases they were guys with intriguing ceilings, but not necessarily the skills to go with it. They were both also behind numerous players at their positions. It wouldn't really hurt the team to have them RS in either case and it would have been better for the player. That said, I can see why Gabe didn't since he was already 19 when he got to Iowa, but in general, a player in his position would have benefited from the extra year.
In general though, I don't like the idea of RS in basketball nearly as much as RS in football.