Underestimate blockchain at your peril

The "real world" is in fact a very good example. Real-world processes contains checks to make sure that nobody empties your bank account or sells your home without your consent, and procedures to undo the damage when the checks fail, or when the process is deemed invalid or illegal after the fact. Code in the blockchain needs to be able to do the same thing. That may not always be possible (you can't take Bitcoin/Ether from me without my consent) but a contract can do something equivalent (hold some coins in escrow, create the digital equivalent of title insurance, create a token which you *can* take away from somebody when legally mandated, …).

Which "unneeded work" would there be in a standard contract? Checking whether the parties involved have enough assets / sufficient authorization to execute it is hardly "unneeded". Besides, drafting and executing a contract in the real world costs way more than twice the coding and gas cost of a typical Ethereum blockchain contract.