It just seems like Anthropic has made a deliberate choice to make themselves a TypeScript dev shop.
From Claude Code being written in React (!!) to acquiring the Bun people so they they could have their very own bespoke JS/TS runtime (and then... rewriting the whole thing), to having the CC "native" app being Electron, etc.
It just seems like it comes down to a choice at the highest level to hire people from a "full stack" background, and build in and and prioritize TypeScript as their dev language, for better or for worse.
I personally think it's worse and that shows in the performance and quality of CC, but I'm biased.
Codex, FWIW, is written in Rust, and it is by far snappier and more reliable, though less featureful for now.