If the data are public already, you're not really changing much by gathering them in one place. More important is the case of private data that are gathered by

If the data are public already, you're not really changing much by gathering them in one place. More important is the case of private data that are gathered by having a user enter their credentials. Using the private data in a way to which the user expressly agrees, regardless of TOS, should be legal. The problem arises when the data are used in a way counter to the user's wishes: like pretending to offer social network aggregation and instead publishing it without consent. That should probably be illegal. I agree that it's not so clear-cut. Like a lot of legal matters, intent is also relevant, in addition to the actual effect.