I agree absolutely. I can stand a protagonist being a "little" evil, but I can't stand an inconsistent character. It's why I detestd Niko in GTA IV - one minute he's waxing lyrical about the horrors of war and how people are used by the powerful to do evil deeds, and the next he's doing those evil deeds simply because he was asked to.
I haven't played Watch Dogs (and given the current state of the PC port, that won't happen for quite some time yet) but I have watched a bit of it on Youtube, and Aiden's just.... he's an absolute hypocrite. His crimes are "justified" in his eyes, even when his crimes are open theft against people on the street. He drains bank accounts of regular people and doesn't bat an eyelid. He causes absolute mayhem and destruction - and does he ever accept some responsibility for the death of his niece?