Uhm, I've worked on my handwriting a lot in the past, before transition, because it was important for me to have a nice one. And through chaotic stages (including one with stars on the i's x.x) I eventually went from something rather messy and unequal to something pretty nice-looking.
I think it's mostly psychological. As in, somewhere within you, you wanted to be more feminine in that way too. Something like that. However it's not like HRT doesn't have any effect at all. With testosterone off from you, you'll tend to clutch your pencil and press on the paper less, normally, which should result in a less "scribbled", smoother handwriting.
Michele: Lol, my job is all about computers, yet I always pre-design stuff on paper before.