I believe the incentives to spread around data by people who are profiting from it are great. Giving in a little bit is not only a slippery slope; it is a foregone conclusion that it will happen to a wide degree, and it's just a matter of time before political parties and commercial list builders and consumer surveillance groups all come together and offer each other large sums of money for the data.
A suggestion I would have for looking into a potential kind of compromise would be to decide that everybody has a right to own their own data. If you want to give a charity the right or permission to share your data with another charity of similar mind, I don't think it's unreasonable to expect that the first charity you gave the information to should send you an email saying they're planning to share your information with such and such a group and ask whether that is okay—“Opt in here to share it”—or at least send you a notification that they are sharing it. Nothing then is done in the darkness; nothing is done under the table; everything is known, and there's a paper trail and there is consent.