I'm a bit disappointed at this. Wikipedia was a disruptive technology desperately trying to find ways to bootstrap itself, not even a decade ago. Back in 2004-2005 large organizations didn't take Wikipedia seriously just like Wikipedia doesn't take Bitcoin seriously now. Wikipedia also had to face their fair share of excrement being slung at them from the mainstream media, when they were new. They should know what it's like. Why don't they give Bitcoin a chance? It isn't any more of a hassle accepting Bitcoin than accepting other non-monetary donations. Ideologically, Bitcoin and Wikipedia are quite similar and could benefit each other tremendously.
Legal requirements for being a registered charity exclude Bitcoin. Laws exclude Bitcoin.
Not at all. Laws may (possibly) forbid or make it hard to claim a tax deduction of money given via bitcoin but not make it illegal to accept bitcoin. If wikipedia is willing to accept it, someone could give them a house, a VHS copy of TJ Hooker, something virtual or even a commitment of work.