Obviously, flac and wav files are sonically superior to MP3's. My opinion, however, is that music is meant to be enjoyed. If folks want to pop a CD into a car or take music with them on their iPod they need to use a supported  format. 

Are they missing something? Absolutely. Is it VERY IMPORTANT? I don't think so.

Just my opinion. The band has an open taping policy, not a distribution one.