Depends, sure it's not the main quality of a software. But it can also hint at some potential features of the language (unless proven wrong) : Speed, safety, potential interest for longer term. You can have ultra lean software written in Java, ultra fast written in Python or simple to understand / develop to written in Rust or C, modern written in C++98, but it's generally the other way around. So, it's not the first thing to mention when speaking about a program, but interesting nonetheless, an element of context.