Has anyone compiled a list of all of the special abilities in OGC prestige classes and their pre-reqs? I'd think at some point you could take all of the special abilities, figure out "when" they could be gained for "balance", and start making new prestige classes out of all of the special abilities, almost at random. (I know I use too many commas, I just love 'em)
I seem to recall that Monte Cook once stated that his original intent for prestige classes was what many of you have said, that they should be tied to groups/cultures, not just souped up core classes.
You can make souped up core classes by making more feats (for example, by turning many of the special abilities granted in most prestige classes into feats). I think someone suggested that.