I type normally below 50wpm (just did a test which scored 54, but that is above my normal day-to-day rate), and I do feel constrained by my typing ability. More specifically not the rate I can spew up finished code, but the way I can't efficiently and naturally use computer (via typing) for sketching out ideas and overall as a tool of thought or an extension of my mind. Indeed I do often resort to pen and paper for that purpose which, in addition to being just plain quaint, simply locks me out of vast arrays of capabilities and tools I'd have on computer (org-mode etc).
There are also other ways I think faster typing speed can transform the way computers are used, for example being more comfortable in the cli, being more willing to write small simple throw-away code snippets, less reliance on tools like autocorrect and autocomplete, which in turn can give more freedom to experiment with more niche tools, and so on.
There's also the personal enjoyment factor. People that run long distances rarely need that skill level. People that sing for fun don't need to do it. It's great to push your abilities just for its own sake. Lots of us just enjoy it.
There are also other ways I think faster typing speed can transform the way computers are used, for example being more comfortable in the cli, being more willing to write small simple throw-away code snippets, less reliance on tools like autocorrect and autocomplete, which in turn can give more freedom to experiment with more niche tools, and so on.