Rust is not well suited for the same things as javascript / typescript / jsx / etc.
Also javascript and typescript are not well suited for compilers and dev tooling.
It shouldn't be seen as a negative that Deno is using rust in places where it really shines, which is a totally different use case than what deno is typically used for.
Other than browser based applications why would you choose JavaScript/TypeScript etc over Rust?
Developer tooling is not complicated and there is plenty of existing tools written in JavaScript, so it seems weird when they rule out there own language as not good enough. It should make anyone think twice before using Deno server side if it is not good enough for themselves.
The parts used to make your car were likely delivered to the factory by a semi truck, and not by another car. Should you buy a semi truck to go to the mall then, since even the carmaker thinks that cars aren't good enough? Obviously not. Different requirements are a thing.
Also javascript and typescript are not well suited for compilers and dev tooling.
It shouldn't be seen as a negative that Deno is using rust in places where it really shines, which is a totally different use case than what deno is typically used for.