People are far too picky, and reject far too many people they would otherwise get along with famously in real life - I've noticed this pattern in myself also. Profiles suck at describing people, not to mention their compatibility with you - yet they have this air of authority and legitimacy about them.
If we had a decent matchmaking service that wasn't just a complete crapshoot (i.e., high-scoring matches are actually good matches), I'd say a blind-date system may in fact work better than what we've got now - get people out there and interacting in real life as opposed to a terminal with a bunch of droll readouts of vital statistics.