Genre Fiction - Why is that term deragatory?

Hiya! My name is Arielle, but you'll probably hear me referred to as Relle. It comes from the fact that if you spell out the letters R-E-L, it sounds a lot like "Arielle." (Say R-E-L out loud, letter by letter, you'll get it.)  Very old nickname, but it stuck.

I would like to start by apologizing for waiting only 48 hours before mentioning my thesis.

That said, I'm writing my senior thesis on detective/mystery fiction, a category of what is often referred to as "genre fiction." After doing the readings for tomorrow's class, I'm starting to understand that "genre" is often used as a deragatory term, something that classifies unneccessarily and unreasonably when more maleable or indistinct classifications would be more appropriate. If genre refers to something which falls into a particular category, something which follows a certain series of guidelines and contains a certain number of recognizable features, then how can anything which has a defined "genre" be in any way original or innovative?

I like to think that formulaic constructs, such as the ones which lead to something being classified as belonging to a particular "genre," allow more room for focus on individual details. If, for example, a romance novel (I do mean romance with a lowercase r, rather than the Romance of the Romantics) follows a certain pattern when it comes to plots, and involves certain different kinds of characters. Each romance novel, or so I have been told, neccessarily contains one of several available stock protagonists, and several available stock romantic issues. On it's face, it seems impossible that a romance novel could create or invoke anything original. But the formulaic structure of the plot allows for more focus on detail, so that although one character may fit into a certain archetype, the author has the opportunity to flesh out that character and create a very original, unexpected sort of person. Formulas do not prevent originality, they simply confine it to certain areas of the text. I wonder if I'm coming through clearly, here, I confess that I'm not sure.

A note to end on: The second article we read for tomorrow's class deals heavily with the idea of the genre as a historical construct, ie "the novel" or "the poem." Genre fiction tends to fall mostly into the category of the novel. I've rarely (read: never) read a mystery/detective novel in verse, for example. How come?