The Last Remnant

I know that captured monsters can be either sold or turned into components. Beyond that, though, is there a third use for them that will come up later? I ask this particularly since, when reading their description, it says things like "Best for making Buuze" or "A rare component," etc. If there are only two uses, why these descriptions? (And, really, was is totally necessary to include the whole "monster capture" system just to get more cash and components?)