I suggest you make Dreamboard offline (no Internet connection), because I don't know what you make with all the dreams, so to become sure that my datas are really private, I suggest to give the choice to make it online or offline. For the people who doesn't care of that, you can still make it online for them. For me, it's not the problem to register one time and then be offline, one time is okay. So there are no problems, thank you very much!
Yeah! I agree with you, they only want to make money with the dreams, because they must pay the server costs and because the app is free, the only option to do this is to sell the informations of their users.