I agree with the overall point, as I’ve mentioned in a reply to one of the replies to this, even though I think Craigslist could use a facelift without losing its great functionality. A design doesn’t have to be ugly to be functional.
Photoshop is not the best example because, at the moment, Sketch is eating its lunch and really cutting into its market share among web / mobile designers. To the point where Adobe was forced to make their own version of it — the newly released Adobe XD.
Photoshop tries to be all things to all people, but when you’re using it to do mobile / web design you’re not using a huge percentage of available tools & they just clutter up the UI. Sketch & its Adobe ripoff XD are much more focused & thus quicker to learn / easier to use.