You know how new writers are advised to do a lot of reading? Yeah, well, this is one of those you-ought-to-read things. But different.
Author/agent Marie Lamba says in her Updating Your Image post that it's not unusual for her to see "submissions that feel dated." For people hoping to get into children's writing, in particular, this is often due to writers admiring the books they read when they were children. That is their idea of great writing and what they hope to model their own work upon. While the authors of that work from another time may have been doing something new, new is only new once. As Lamba says, "really great fiction of our time reflects today’s sensibilities and your experiences as who you are right now...Writing from a place that only takes in what fiction once was like too often just feels pokey." I would say feels "done," myself.
So when you're doing your reading, keep up-to-date. Read widely and read what's being published now, as well as rereading what was being published when you got excited about books. Think about this: In what other profession would you not keep up on what is being done in your field?