I think there are varying levels of assurance that developers need while writing software. I tend towards stricter languages with more guarantees, like Rust with its borrow checker and Coq with its powerful types and proofs. This doesn't need to be a universal preference, though; my preferred work is in compilers, which requires a high degree of assurance, and I study programming languages formally.

The largest barrier to greater adoption of languages like Coq with proof systems built-in is the formal background needed to get started. I think that Rust has done an excellent job at making stronger systems more accessible, but it takes a lot of conscious work.

With JavaScript, I think the idea that performance in language design can be an afterthought, made up for by world-class optimizing JIT compilers, is fundamentally wrong. It doesn't give users a meaningful way to easily reason about the performance of the programs they write. The main implementation of Python, pythonc, is essentially an interpreter over an unoptimized bytecode format, giving it poor performance. I think performance considerations should be a fundamental part of the language design.