It also altered my handwriting with a ballpoint. Fountain pen or pencil seemed to not trigger "palm mode".
Like you say, if I'm writing longhand with a good pen, I wouldn't write this way; but it definitely shaped my writing. Also, I learned cursive in 1st grade. I got my first Palm Pilot in 6th grade. It peeled back a lot of my writing style...
Really the amount of time I spend trying to just stop Android from using the wrong autocomplete words is less than what it took to jot letters out on the Palm...