Writing is back and in good form in The Sims 4. There is still a writing skill and one still needs a computer to work on their writing. There are also a number of improvements and additions to the writing system.
When you want to start writing, you go to a computer, same as it has been since the Sims 2. When you are unskilled the only two options are to practice writing or to start a Children’s book. As your Sim grows in writing skill, they begin to unlock new book types. The types I observed were: Children’s, Non-Fiction, Poetry, and Screenplay. My Sim did not get anywhere near to maxing her writing skill so that is NOT a comprehensive list, but that was all I observed in my play time. Different book types take different lengths of time to write. Children’s books and poetry books are fairly quick to write compared to Non-Fiction.