This is very similar to how I look at it. Expressive editing features do not have a direct impact on my productivity when coding. However, for those 1-2 hour f

This is very similar to how I look at it. Expressive editing features do not have a direct impact on my productivity when coding. However, for those 1-2 hour focused coding sessions, it is easer for me to enter and stay in flow when I feel a better connection to my tools. Since I do perhaps a dozen of those a week, I am able to accomplish more and do it more enjoyably, even if I only spend 20% of my work time in one of those sessions. I am not sure exactly how much the productivity increase is because I haven't tested it rigorously (honestly not sure how to even measure that), but I'd guess it's still only 5% at most. The benefits to my happiness and fulfillment when coding are definitely noticeable though, and I think it is because I am able to spend more time in flow. Edit: and for what it's worth, there are things that arguably have much greater impact on my ability to stay in flow than just the text editor: how good the debugger/REPL is, my familiarity with the language and libraries related to what I'm doing, etc.