But jumping to "Hey, it's free software and you get what you pay for!" if people gripe about it doesn't help the case for open source at all.

It doesn't help the naive case, but I don't care one whit about the naive case for open source or free software.

The reason I believe that open source and free software can reach higher levels of quality and utility and applicability than proprietary software is because open licensing gives a wider community the opportunity to improve the software.

The real response really ought to be "If you're part of the community, the quality and applicability and utility of the code is your concern too. Contribute." Contrarily, if you don't contribute in some means, you're very clearly not part of the community and your opinion about the code doesn't really matter.