My DD hated writing in preschool (age 4/late B-day) but I thought it was way too young anyway. I learned to write my name in 1st grade! And it took alot of my energy. Before that it was playdough, doll clothes and hair, drawing with crayons...it was so, so long ago in a Mr. Rogers' world.
My DD did like to take a stick outside and dip it in a puddle and write letters on the driveway and watch it evaporate. She did this herself though, her idea. Though I still don't think she was 3, maybe 3.5 on toward 4, before she went to preK.
I've heard of kids using fingers paints on big pieces of paper and writing letters in the sand, though again I don't know at age.
Neurologically, and physcically, I don't think young humans have caught up from an evolutionary standpoint to what is being asked of them at such a young age. There were always the kids at storytime etc. at age 2, 3, 4 where I took my DD who could write letters and do little fussy crafts and I thought "good for them" but I didn't feel bad about my own child, since I thought honestly it was a bit young. If they are leading the way, definitly follow and support them but don't push...that's strictly my opinion.
