After being stuck in XML land for making UI for almost two decades I couldn't be happier to leave it behind.

Spreading your code over multiple languages means you now have a bunch new fun edge cases to deal with when things get stuck and don't update correctly. With everything in one language that means all debuggers and other tools work the same regardless of where in the app I'm debugging.

I've found it fascinating to see UI building come full circle. I started in code (C), then using various XML schemes and now back in code (Kotlin, Flutter, Swift). But a big part of why it's nice now is because C is a pretty horrid language for making modern applications.

QML is nice and the bridges project could bring it to more languages. https://slint.rs/ Is similar but written in Rust although.

I don't think it's underrated, it's just that everyone builds for the web nowadays and it isn't like they don't have good reasons.