Just to be clear, I don't support SOPA/PIPA, and I'm all in favor of the blackouts. I don't think it's an abuse of power. As a display of power, it's a little bit unsettling. Ask yourself, if Wikipedia went dark over something you didn't agree with, would you be OK with that? Along the same lines, are you OK with them not going dark about other things you may care about?
The bill threatens the existence of Wikipedia itself, its their right to do whatever they want to protest it. I think your're misjudging the situation a bit. This isn't the same as protesting some random cause, its something they believe can directly affect their organization's continued ability to serve its users.
Again, I don't support the proposed legislation, but the rhetoric of "this bill threatens the very existence of Wikipedia" is a bit hyperbolic and may harm the cause.
I know it's not just some random cause, but it makes me think of questions like, "what would happen if Wikipedia (or similar entity) were to go dark until we got marriage equality?"
Yes. I would. Whether it's something I agree with or not, they're an independent entity. It might change whether I'm willing to do business with them, but I'm not going to wail and rant and piss and moan. They're under no obligation to provide service to me NOR are they a necessity.