If you take out a loan from a loan shark, you should probably know what to expect. That doesn't mean that the loan shark isn't breaking the law when you get roughed up for non-payment.
People who go to loan shark know exactly what they're getting into--borrowing money.
People who signed up for unroll.me signed up because they got sick of all the the spammers and wanted to get away from all that easily.
Most people including me, thought they would somehow monetize with ads or something like that, but never thought they would sell our info to 3rd parties like this. So No, it wasn't at all obvious what to expect.
The saying "power corrupts" is more correctly expressed as "power attracts the corruptible".