i bought more than 30 master sites in the last 3 years, with a total of 2M members, and i can tell you the same as you did... the "Whinners" never contribute to the life of the whole, they whine for their own nostril...

actually, what you could do is beat them on their own game... start polls before you implement a feature... as you can see who voted, you can also see if THEY vote and what is their contribution to the mood of the site. Another feature would be to give votation level only to the ones who contribute to the life of the site, by postcounts or donations etc...

Something i always do on major sites, even if they are not from me: master features are activated only to members who are "attractive" on the site... people who post interesting stuff, and people who are inviting interesting people...

otherways you can ban them.. lol