On the contrary, it is absolutely crucial for some of us (yes, even for developers). I work with an interactively compiled language (Clojure and ClojureScript) and while I rarely do full "builds", I care a lot about recompiling single files and reloading them in the browser. That is not a multi-threaded job and requires single-threaded performance.

This is why when looking at iMacs, I'd rather get the iMac than the iMac Pro. Multiple cores just aren't as important to me as is single-core performance.