Risk assessment is literally the entire product is it not? Loans are not a technical problem to solve, and there's no inherent usefulness in it being a smart contract. A guy in a office is not a risk assessment strategy.
Your ownership in a loan on Dharma is denominated by a cryptographic token like Bitcoin, Ether, or any other, meaning its just as easy to trade your stake in a loan as it is to trade a cryptocurrency.
Assets built on open protocols are fundamentally easier to build products and technologies around -- insofar as they lower the barrier to entry for developing financial applications, their openness is extremely valuable.
Also if you're loaning in ETH, but presumably people need the loan for USD-based operations, what do they do when the price of ETH spikes?