Your definition is the thing I hear a lot. It makes sense in the abstract, but when you start applying it to actual examples, it breaks down. I will refer you to the "Can you fry that?" skit from The Community: http://m.youtube.com/watch?v=qcjse8Opobw.
Basically, unlike what your definition suggests, some art is objectively better than other. Some art takes more skill and invokes more and better feeling than other. Take a look (ideally in person) at Rodin vs Shapiro's work. See which makes you feel more and more intensely. Modern artists substitute enthusiasm for skill way too often for my taste.
Skill is not the point of art. Feelings of the beholder are. If you create hyperrealistic portrait then the creation itself is worthless for me because it evokes no feelings because it looks like yet another magazine photo. The process of creating hyperrealistic portrait is worth more as a piece of performance art because at least it evokes some feelings.
I agree that some art can be in some sense better than other. But the only thing you can do is gather statistics about what feelings and how strong any given piece invokes in some population sample. But feelings don't have clear definition of better. Also statistics doesn't have it either. So even objective comparisons are subjective because you have to subjectively choose what you objectively compare.
Basically, unlike what your definition suggests, some art is objectively better than other. Some art takes more skill and invokes more and better feeling than other. Take a look (ideally in person) at Rodin vs Shapiro's work. See which makes you feel more and more intensely. Modern artists substitute enthusiasm for skill way too often for my taste.