I think the question isn't "Should fantasy include romance?" Instead, I think we should be asking "How much romance?"
The truth is that EVERYONE loves love. There is something wonderful about falling in love, finding that special someone in your life, and sharing your heart with your "soul mate". No matter how cynical you act, there is always a part of you that can't help but smile when you read the story of two people falling in love.
But when it comes to WRITING romance, you have to walk a very fine line. Too little can be just as bad as too much emphasis on romance. If you don't do it right, you could turn an epic fantasy or sci-fi novel into nothing more than crappy genre romance.
I love writing romance as much as the next guy or gal, but here is what I tell myself when I write romance into a novel:
- Keep it relevant. Is the romantic sub-plot going to help develop my character or story? If not, it's just distracting from what's really important: the MC's journey, growth, and development. Romance can play a central role in character development, but many writers throw it in there just because it appeals to readers. Make that romance relevant to the story, and it won't feel like it's there "just because".
- Keep it in its place. How many chapters of an epic fantasy novel do you really need to dedicate to the budding love between two characters? Romance and relationships have their highs and lows, but most fantasy readers aren't picking up your book because they're looking forward to a spicy romance. That's not to say you should trim it back or eliminate it, but simply keep it in its place.