This in a larger perspective at least, IS a problem for NGO:s from what i know. That donors seems to be much more careful where they money go when its in the form of a donation. I dont know about open source project specifics here. I totally get what you mean and probably mostly agree as well, but the money you give to corporations have consequences as well. You can for example fund a company you have strong moral disagreements with without knowing or miss a company that you would want to support for the opposite reasons.

With that said I also think we should expect more then "it helps fund the development". Its not that difficult to write a couple paragraphs more and be a little more specific. Then again, maybe they get so little in donations that they cant really say how the money will be used and its more of a "buy me a beer" type of thing to keep the developers happy. Unless suddenly people start giving more and a developer actually could invest more hours in the project.