"how can you use a computer for so long and not get used to not looking at the keyboard ? "
Saxon,
It's just a learned behaviour I guess. A bad habit once acquired is difficult to shake off, especially without a powerful incentive to change.
When I first started pounding IBM keyboards, there was no internet, no email and the sort of thing I'd be typing would be commands to mainframe OSs from the operator console like
r 00,'i $3p'
s rdr
r 00,'i $3d'
s wtr2
progressing to keypunching cards like
a la 4,24(3)
b sr 3,2
c mvc 16(4,2),(8,3)
whilst writing assembler code.
It was only towards the end of my 20 years that an online internal mail system came to pass and I started to write in real English, and I didn't write anything long enough to warrant the effort of learning to touch-type.
In the interim years, when I wrote technical newsletters, they'd be typed on a golfball by the dept secretary and sent to the print room for duplication.
My brain is just programmed that way permanently now. If you try too hard to think consciously about how you do something which has become automatic, it throws a real spanner in the works.
I spent 2 months in New York driving a rented automatic and when I was in the last week and about to return to driving my MGB in the UK, I tried to remember how to change gear with an imaginary clutch and gear lever, and began to panic as I couldn't quite get it.
As soon as I was home, of course I drove away flawlessly, without even thinking about it.
Once these things are hardwired inside the skull, it takes a lot to shift them.