Earlier quoted context omitted.
Right now contracts are enforced by lawyers who can interpret code that is not fully specified. I would guess that hiring a contract developer to create a water-tight contract the computer is capable of understanding would be much more expensive than a lawyer. This is in a similar vein to the fact that it's more expensive to have programmers create a perfect NLP app to translate something than it is to just hire a tr…
I'm sure creating the first spreadsheet application was more expensive than hiring an accountant. But not doing it 1 million times. Someone will make "contracts as a service" and competition will drive down the cost, until it's nearly free (as spreadsheets are today).
Smart-contracts are computers trying to be human. Most contracts are flawed and only really matter when things go wrong. I'd rather that a human be there when things go wrong to understand the human intent behind the contract than have a computer which does not know the human intent, but is able to enforce the (likely flawed) computational representation of that intent.