But real world contracts are never 100% clear, and can be modified retroactively in court when their terms violate the law, are vague, or are otherwise deemed unenforceable.
Unless the attacker is careless enough to reveal his identity, or puts his ill-gotten gains at risk of being hacked back, or the victims are Ethereum foundation members, your chances of restoration are slim to none.
Except that in real-world contract and criminal law, there are various mechanisms that attempt, with some degree of success, to dissuade fraudulent behavior and allow for some form of restitution. Blockchain currencies, on the other hand, have been promoted partly on the premise that they are free of this sort of governmental interference.
You can put anything in "real world" contracts (in a 'put words on the paper' sense), but there are things that would be considered illegal if brought to court. In a sense there are reasonable defaults. So if you sign without reading a contract that 'you sell your self as a slave to me' this contract would have no power because slavery is illegal.
More accurately - judges and lawyers interpret law, contract and otherwise. This sort of interpretation is explicitly ruled out in Ethereum's case, except when enough stakeholders decide it's not.
