I don't agree...
Writing is all about rewrite, rewrite, rewrite. It's good to get those ideas out quickly and openly, and then revise, revise, revise.
Being afraid to write freely just burns your creativity - you start to play it safe in your head.
Embracing the flow of the story is a good thing in early stages of writing, and you shouldn't try to restrict yourself with the type of thinking you described in your post.
I have no problem with a typewriter, they're nifty little things to have, even just as decor, but I have to disagree with your reasoning behind having them.
My opinion anyway.