When I do fantasy, it's really just really soft sci-fi in a setting where people have developed a technology called "magic". Which is to say I just really dislike fluffy, high-fantasy magic, and the idea that magic and technology are fundamentally different forces that cannot coexist.
That said, regular cross-genre stuff isn't really new enough anymore to seem like a good idea without something to really make it work, or make it stand out. You can't do just wizards-and-laser-guns and call that a hook, you know? Maybe part of it's because I follow all the MMORPGs in development, and we're frigging well drowning in sci-fi games that shoehorn in some kind of quasi-magic system (often handwaved as something like nanotech or psionics, but otherwise following magic tropes to a T), presumably because the developers don't dare to make a game that isn't essentially World of Warcraft.