There are more prospects in the system but not all are of equal value. They are a finite resource. I can't speak for all of RZ but I have no fear of moving prospects because of what they may be some day. I fear giving them away for a disproportional return. Why give away what you can sell?
The only answer I can come up with is the difference in perceived value to this organization and that of perceived value to everyone else. I feel the organization thinks this is a good move because it will let the fans know they are trying to build a winning team and because of that the fans will continue to come on down and watch. The pro's and con's of that model have been rehashed many times.
Scott Rolen embodies the status quo to me. I think most fans are sick to their stomach of the status quo while ownership is quite content with it despite being misquoted about wanting to win from time to time.