Memory safety, for one. A whole lot of better defaults (e.g. immutability by default). Then the influence of functional programming. Nice async primitives like coroutines.
It's not just Kotlin and Swift. Rust is nice as well. Even Java has actually improved a lot over the years.
Only C++ seems to get worse over the years. It's the only mainstream language where people say "if you limit yourself to a subset of the language, it's actually decent". And every year, C++ brings new stuff that people probably shouldn't include into their "decent" subset.
> You also forget tho, that Linux does exist with a growing popularity
I have been a Linux user for 20 years, I don't forget it. My favourite UI is a CLI, and there, languages like Go or Rust now often make more sense than C++. I am hoping that good desktop GUIs will come eventually, because I absolutely hate the web-based stuff like Electron. Maybe with Compose multiplatform? I hear Flutter is decent there, too.
> I've started GUI development because I was on Linux and most apps had horrible UI/UX
Except for IDEs (I like the JetBrains ones) and browser, I don't use GUIs :-).