I think we can have it both ways, within reason: we use the star system to get a rough feel for how well recruiting is going relative to other years and to other teams. We can't all have the access or expertise to judge this ourselves. At the same time, we have confidence in our coaching staff's ability to choose and develop players, so we trust THEIR judgement.
What I'm disputing is that the ratings are "either worthwhile or they aren't". They are worthwhile to a point.