I'm not a Romance fan. But I enjoy Romantic subplots. Do I contradict myself? I don't think so.
Romance novels are required to have the Happily Ever After ending. You pick up a new Romance genre book, and without peeking, you may correctly assume that both the heroine and the hero survive until the end and become a permanent couple (or threesome, alien-creche-parents, legal partners, or whatever term applies to them). The genre is formulaic in this way; if you do not provide the reader with a HEA ending, it simply will not be classified (by readers!) as a Romance. And they'll complain and never read your books again.
So, without that HEA, what genre is it? That depends. My first guess would be Chick Lit, but it could also fall into Literary Romance or Women's Fiction. Stray too far (i.e. less than half your plot concerns the relationship), and your book could be Romantic Suspense, Romantic Fantasy, Romantic Comedy, Romantic Adventure, etc. You want to cash in on the vast Romance market, you need to put in that HEA.
For me as a reader, it is the formulaic nature of the Romance genre that turns me off. It's the most restrictive genre I can think of. Romantic characters enter the plot at the beginning, various delaying/distracting stuff happens to them in the middle, and at the end, they always, ALWAYS, end up together. It's far more strict than even Mystery, in which you always know the crime(s) will be solved at the end. With mysteries, you don't automatically know who will be guilty of the crime, and every book is a new puzzle to solve. There's no such appeal in a Romance. You know who the romantic players are.
I suppose it's a combination of my own past romantic life, my love of the unknown, and my cynicism that makes me disinclined to read Romance. Many people who read this genre do so purely for the happy ending, the fantasy of the HEA. And I get that: I want happy endings in the books I read as well. But the shiny pink glowing happiness at the end of every Romance book ever just says to me, "If only you were as awesome as we were, then you might get some of this for yourself. But you're not. Poor you." And I must emphatically reject that notion, because I am neither more pitiful than nor less awesome than fictional characters. I'm not inclined to follow the lives of the rich and famous in the real world, so why would I want to read about fictional people with glorious, perfect hair and D-cups* getting exactly what they want? How does that make me feel better about myself in any way whatsoever? It seems like some bizarre literary addiction, in which I'd need to pick up another Romance right away lest I realize how sucky my life is in comparison to the fictional couple's.
All that said, let no one confuse my distaste for formulaic love with a hatred of the romantic in other genres. Romance in a plot is like an ingredient from a recipe. If it's all you have, all you get is flour, or lemon rind, or BBQ sauce. But add the other ingredients back in--suspense, mystery, historical drama, adventure, sci-fi--and you get a more balanced--and to me, palatable--recipe. Romantic subplots enliven a whole book. I've got three or four of them in my own adventure fantasy series, Legend of the Shanallar. Romance will play a distinct part in my upcoming Mystery series, Margarita Williams Geocaching Mysteries, too.
Romance should be a natural extension of the rest of characters' lives, as they interact and suffer hardships during the advancement of the plot, not something forced into corsets which artificially shape the body of the story. Or whatever they think will make them look hottest. Come on, Romance genre, whatever happened to loving yourself for who you are?
I know, Romance books sell like hotcakes, but I'm a waffle girl. Give me dimension, texture...and then give me that whipped cream. ;)
* Yes, I know what you're going to say. But you should know what my reply will be. :D