Not all donations go to the society. The hall needs to cover expenses too. In my hall, we were asked to attend a meeting once. All male publishers, regardless of what kind of privileges you were spiritually mature to deserve, had this one privilege. To attend a meeting were we were told the hall did not have enough to cover the current month.
True as well it is that the fact that they are asking for money is not proof there is a real financial problem. I do happen to think there is one because other evidence points to it. At best, the hardship may come not from a lack of donations but from the growing pains of transition. I happen to think that the WT is transitioning from a voluntary donation/voluntary mag subscription type of business model to a more real state dependent model. That takes time and some initial expenses to survive while the new model kicks in. I believe we are all going to see our halls changed at some point in the future. Unless you are in a hall where the real state market is busting, then you may get relocated. Other than that, the new model will demand that your hall gets changed for the new design. It is more efficient in every way.