But because of those things, he is not what I would consider credible opposition. Again, he's the show's Archie Bunker. A caricature, really.
Isn't this circular logic? Discounting the Ferengi as examples of people who go against Starfleet philosophy simply because they aren't credible is ultimately self defeating, I'd say.
After all, this means that any species that is against the starfleet philosophy and not a bad guy thug is eliminated, and so of course you are going to be left with a list of people who are against starfleet philosophy and also bad guy thugs. Kinda silly then to wonder why the list is filled with thugs.