Well, if you follow the link, you'll see 50.4227 % of all Mastercoins (at the time of writing of that doc) are held in 17 addresses. So yeah, there is definetily a concentration of power, so to speak.

Nevertheless this might be addressed by the way votings are done, say for example very critical things need at least 75 % agreement between all voters. I get your point and share your concern to some degree, but it would be a step in the right direction, right?