An author I admire recently went on a rant on his blog about the way literature classes are taught and how in-depth analysis ruins reading, and the best way to write was to write without thought of theme or subtext – just to get the story out.
There’s some merit to his points: over-analysis can make a lot of people tune out, and spending all day on one comma is an utterly ridiculous waste of time. But it’s fun to insert layers of meaning deliberately. Writers can’t help putting in a lot of their world view in their writing, which is part of what makes books like Lullabies For Little Criminals fascinating to read.
If a writer is used to reading analytically and approaches writing similarly, then they can insert the ideas they want into the piece, deciding themes and motifs actively as opposed to letting them rise naturally from the story if they arise at all. Neither technique is superior, but having the training in literary analysis necessary for it to be a deliberate process is not a bad thing.