It's not better architecture so the gain is few pennies more per chip at cost of A LOT of work... work that can't just run Android or much else out of the box.
I do agree that it takes a lot of work to get something usable, and so I think we are a ways off from mainstream risc-v. I do also think there is a lot more value for low power devices like embedded/IoT or instances where you need special hardware. Facebook uses it to make special video transcoding hardware.