An interesting discussion is going on over at Nathan Bransford's blog. Bransford's an agent, and he wrote a post on Tuesday reminding all of us English major types that when we write query letters, we need to Knock Off the Analysis Already. Agents don't want to read queries that talk about all the high falutin themes (love, loss, evil, capitalism) you "explore." They want to know what happens in your story. The plot. Even if your book is literary. So, I knew that, but I do need to be whacked with that reminder now and then.
But then a bunch of commenters wrote in to say that they *only* wanted to be storytellers, entertainers, light fun fluff-makers, and anyone who deals in themes at all is a pompous ass (I paraphrase). So Bransford has written another post re: no, literature is not really that democratic, and trying new, difficult stuff is good. Only, sometimes, really tough stuff doesn't sell. It's the usual problem. You are most lucky if you are good at writing gripping plots that just naturally throw off sparks of meaning as they barrel forward. If your gifts and / or ambitions are more complicated, then you have some choices to make.