Smart contracts and Ricardian contracts can not be equated despite the fact that they share a series of similarities; they are independent notions. It is possible to implement a Ricardian contract as a smart contract, but not all Ricardian contracts are smart contracts and in the same way, not all smart contracts are Ricardian.
My team and I are doing some research regarding human-readable smart contracts. This is because Grigg said that a digital contract should be readable like paper but also processible by PCs. It is an interesting topic and there is lot of work to do. However, it would enable more people to create and understand smart contracts.