I wouldn't donate to a charity which simply billed that they were aiming to cure Alzheimer's, either. I'd want to know what they'd accomplished so far, what they were planning to use the money for and, critically to the discussion at hand, if expenses seemed out of proportion with the activity I'd want to know why.

I don't claim in the parent comment that Wikipedia don't justify their expenses (although I don't think they do so sufficiently). I'm responding to the specific claim that there shouldn't be an expectation by donators to understand the benefit of their donation.