Genuine question: why js?

Why not something like c#: native, fast, crossplatform, strongly-typed, great tooling, supports both scripting (ie single file-based) and compiled to a binary with no dependency whatsoever (nativeAOT), great errors and error stacks, list goes on.

All great for AI to recover during its iterations of generating something useful.

Genuinely perplexed.

If I was to pick a language, I'd pick the one all developers agree is the best.

Sadly, this will be the trend with things moving forward. JS is perceived as a good language and LLMs are meant to make them even easier to write. It is not about the mertis of a language. It's about which languages LLMs are "good" at.

AI are good at JS because basically there is a ton of JS code available publicly without usage restriction: the JS code published to be executed in your browser. Most of JS code attached to web pages has no explicit license, but the implicit license is that anyone can download it and run it. Same for HTML and CSS. So using that public code to train models is a no brainer.

Because js became an everything language that everyone can write and its the only language you ever need.

I dislike it also..

You could make a better argument for Go (compiles to native for multiple targets, zero actual dependencies (no need for a platform or virtual machine on the target)