Especially with LLMs to assist we don't gain much anymore from making everything one syntax, one language, etc. Projects like Dotnet Blazor/ASP.NET or Python Streamlit/Dash IMO are forced and are more trouble than they are worth. The OP suggestion, where everything is Rust, has the same problem; it's too forced.

We should embrace the domain-specific niceties; there are room for lots of languages, they can iterate more quickly, try new things, and specialize syntax to the domain.