I would love to just let the " school " do it but well...thats not going to happen, they will just complain instead. I do think writing is as important a skill as reading and math so I want to make sure my son even if he hates it can write properly. This means getting it from his head to paper. Without great writing skills education becomes harder and harder the higher you go.
I do not take a lot of his free time working on it, just enough that over time the improvement starts to show through.