I did not say that game time guarantees that a player will turn out to be great. But, one thing is sure, not getting to play will guarantee that a player does not develop into a solid contributor.
Here are some guys who didn't play a ton of minutes early in their career but many folks would say were decent contributors by the time they were starting:
FCM (15mpg or less fr/so years, 18/25 mpg jr/sr years)
Garrett (14mpg or less until senior year, 25mpg)
Robbins (6mpg or less fr/so years, 17/27 jr/sr years)
Again, there are only 200mpg to go around, so you probably won't see a lot of minutes go to the 8/9/10th guys on the bench unless it's a blowout.
I think the reality as others have stated above, is that we probably have a lack of talent in our bench depth. The guys above were all limited minutes fr/so years, and then role players in jr/sr years. We don't have that many guys who did nothing in years 1-2 and then burst out years 3-4 (maybe Harper). If guys are good, they will play (TJ, TA, K0, CL, etc.). If injuries occur, guys will also play, although they may not be ready or an upgrade (SDJ for instance). I think we've had some gruesome recruiting the last several years, so it's very possible that no amount of real gametime was going to turn some guys into role player types their jr/sr years.
If you look at our bench right now, the realistic candidates for this are Paul, Jesse, Julius, Kovien and Khwan. Khwan was getting 20+mpg down the stretch. Julius averaged 8mpg, but it was definitely on the rise end of the year. I disclude Jesse from the analysis because I think there was an off court thing going on there. Paul and Kovien are the question marks. CM could be bad at developing them, or they could just not be quite good enough to earn time.