Smart contracts are NOT contracts. They are software that run on the EVM. That's it.
Absent the existence of a functioning and accessible legal system to mediate the resolution of disputes, smart contracts can serve the societal purpose otherwise served by traditional paper contracts.
Yes, smart contracts are not paper contracts disputes over which are judiciable by a court, but in many situations smart contracts can replace paper contracts, reducing or eliminating the need for courts to intervene in the first place.
Yes, Ethereum's security model is a problem. There's no reason to believe, however, that it won't be improved upon.