It's not the wrong design; RISC-V is designed around extensions, and they left room in the instruction encoding for them. They don't have a 800-lb gorilla like Intel shoving the ISA down customers' throats (Canonical is the closet thing) so there is some debate on which combination of extensions are needed for desktop apps.
FWIW I wrote this article a while back all about RISC-V extensions and how they work at a low level: https://research.redhat.com/blog/article/risc-v-extensions-w... page 22 in this PDF: https://research.redhat.com/wp-content/uploads/2023/12/RHRQ_...
> They don't have a 800-lb gorilla like Intel shoving the ISA down customers' throats
Nobody really forces you to use x64 if you don't like it, just as nobody forced you to use Itanium — which Intel famously failed to "shove down the customers' throats" btw.