Isn't the goal of touch typing that you no longer have to look at the keyboard? So you can still be paying attention to the screen while typing, i.e. you're not going to type 30 commands before noticing that something is off.
Touch typing you usually end up basically 'sending the commands' to your fingers before you put much though into it. So if you are off by 1 char or forget which mode you are in you can really destroy yourself. Most touch typing is also taught without you even looking at the paper/screen. The idea is your imagine what you want expressed and your fingers just 'do it'. I have done both of those things hundreds of times. I will do them again. As typing is just something I do not put much thought into until something is very wrong. At 90WPM you can get a lot of chars in before you figure out you have reallllly messed up.