You'd be surprised how many senior-level people are hunt and peck typers. I've met several software engineers with 10+ years of experience who don't type with all 10 fingers (assuming they have that many).
It's not so much "touch typing", it's being efficient with the main tool (the keyboard) that you use to interact with the computer. You don't need to be a 60 wpm typist, you just need to be able to communicate without stopping everytime to find out where the "@" symbol is.
This is not about typing faster. This is about lightening cognitive load. For instance, I don't use my vision to type. Rather, I think "stretch my right ring finger to get the [O]" (except I don't actually verbalize it, it became automatic now).
That mean my vision is free to concentrate at the screen. That means that my short-term memory don't have to memorize what I am currently seeing at the screen. This means I have more precious short-term memory to do whatever important task I am doing, like, programming.
Subjectively, touch typing is surprisingly comfortable. So even if I'm completely wrong about the above, I still feel better, and that alone is worth the investment.
Why am I belaboring the tuning thing? Because learning how to tune your guitar properly is basically a tools issue. Many guitarists are perfectly happy to get by with poor tuning, but then they sound bad even if they're playing well. Developers are often content to use whatever tools they've got, without digging in and figuring out how to "tune" the tools for maximum efficiency. Mastering the tools of the trade is an important part of every professional's ability to be effective. - Steve Yegge
Faster typing is more code is better. Seems pretty straightforward to me.
Now, does doubling your typing speed also double your productivity? No, of course not, you spend time thinking, looking through code, reading specs, searching for solutions, compiling, etc. But I don't see how improving your typing speed would not result in at least some productivity gains.
