I woud go with Tony's thoughts. We are in the business of providing weather data for others to see, so by raising funds to keep their site going, albeit the back of our data, they are giving our own sites exposure. In my old trade as a photographer I would have to pay for that. Financial gain for my data would of course be welcomed, I have after all a weather station to support. But I am happy that someone may be able to use my data, and thus my efforts have not been in vain.
I may well review my thoughts if it is shown that they are making huge profits on the back of our work (sounds like banks doesn't it), but for the moment I will wait and see.
Best wishes
Mike