This is a pretty subjective question... However, I'm game. :)
Skill, obviously, helps a great deal especially when you have to react to the moment and be able to adjust quickly for that. However, that alone isn't going to create a great photo. An old adage was f/8 and be there, indicating that you should forget about the camera and get the image. Easier said than done, sometimes, and one gains confidence to do that when they've built a lot a skill around their equipment.
Art is often in the eye of the beholder. One man's art is another man's trash, so it goes with the artistic eye. Now, that's not to say that there aren't images that will take anyones breath away, but I have a feeling that these are so statistically rare that you may have a better chance winning the lottery than capturing one of them. Mind you, you never know! I suppose that's what keeps us snapping. Anyways, I'd hardly consider myself to have an artistic eye, but it's something that can be trained, I think (I hope!). I'm working on it, lots of flops, but I get the odd one I'm happy with.
I, honestly, doubt that theoretical knowledge has very little impact, if any. In fact, I'd wager it goes the other way. I know people so caught up in the theory that they fail to see the image. This isn't unique to photography, I see it my industry too. I've seen a number of software developers with deep theory that couldn't deliver a "hello world" program because they'd be stuck debating on the best algorithms for doing it.
A lot of practice? Bingo! Why not fire until your finger wears out? Just delete what you don't like. You can take hundreds, even thousands, of images and even if none turned out, you may learn from them. The quote chills42 listed is a good one, but you do have to take some time to look at the outcome and try to understand why it missed, or why it hit, otherwise you're just pressing a button.
After all that, the camera is just part of the bag of tricks skilled photographers have to make their images look great. Many of these tricks also existed in the darkroom, but digital brings more of them to the masses. A lot of shots you see on sites like Deviant Art didn't look like that coming out of the camera (though some may have, I don't want to disparage). Some of these are going to be fairly basic changes such as adjusting contrast, saturation, vibrance, sharpening, and the like. Others start to get more interesting when you crop, rotate, clone out parts, and more. What is your goal? To create art or to capture precise information at that moment in time? If it's art, you can get very creative after the fact and why not? After all, the goal is to provide an image that gives the viewer pleasure.
Anyways, don't get discouraged because there are better photographers, for all but one in the whole world, there always will be. Just get out there with the camera, play around, and make mistakes. Most importantly, have fun and just enjoy the moment of the capture.