I really don't know. I suffer in both directions. I build large projects on a daily basis, so picked a Threadripper. It destroys large builds, especially C++ ones. Then I use the same computer to play games, and the CPU can only spit out 300 frames per second when my monitor can display 360, which is annoying. (It's CPU limited, not GPU limited, sadly.) So really, I want both, and nobody has both.

Single thread performance is going to be especially relevant if you are developing an older language. I'm always surprised how slow webpack is (and don't do enough frontend stuff to mandate that people switch to that Go equivalent), for example. If you have good single thread performance, you make a lot of Typescript developers happy. If you have good multi thread performance, you make a lot of C++ developers and gamers happy. So having both would be great ;)