Fuji,
The difference here is that we are NOT shareholders of this limited company, and so we have no powers to sack anyone. We either choose to continue to buy its product or not, and at least it seems that there is the option of volunteering to help to define the "product".
Again, I think its website is a little misleading, but at the end of the day, I joined not because of the IMC, but because I understand that AOPA does good work in other areas.
I don't like monopolies, but if AOPA was the only game in town for the regulators to talk to "GA", it's hardly surprising that they've acquired this quasi-official "voice of GA" status. There is always a danger in these circumstances that organisations in their position actually start to believe that they alone have the authority to speak for whoever they claim to represent, whether the punters want this or not. I'm not saying this is so in the case of AOPA, because I don't know, but this is where campaigns such as your IMC one often bring immense value outside of their stated aim by reminding every one that there are other views which must be considered, and other voices which must be heard.
This, aside from the fact that I agree with its aims completely, is why I wholeheartedly support the IMC campaign.