Dour fiction

I've been noticing a trend in fiction; books which are consistently dour, dark, and without resolution. I'm wondering if these qualities are the current definition of "literary" for fiction? Is a book "commercial" if a protagonist moves from conflict to resolution, from weakness to strength, from darkness to light? Are people less smart, refined, and enlightened if they want to see progress? Does being smart, refined, and enlightened require assualting yourself with hopelessness and a belief that life essentially sucks?

If so, I guess I'm doomed to be a commercial writer.