I think one of the problems you have in your definition is that you're using, what I consider, to be the worst word. "Good." It's the vaguest word we use every day. Good person, good idea, tastes good, feels good, you're a good guy. All completely different meanings. Moral, potentially useful or inspiring, pleasing to the taste in at least one of many different ways, pleasing to to tactile or emotionality in at least one of many different ways. useful or dependable.
Good in most cases is defined as relative. Often subjective. "That was a good movie." "Why was it good?" "Because I really liked it!" Totally subjective.
You argue that there must be something definitive about good art because it becomes popular. You then say that it takes more than that. And must pass the test of time. But you haven't defined "good" yet. I also don't believe in a "test of time." What does that mean exactly? It has to sit around for a while and people have to keep agreeing about it for it contain worth?
Let's talk about the real reason that the art world has critics and rates and ranks pieces of art. Money.
How do you as a person, sell something, if it has no definite value? The art of selling is about creating perceived value in the mind of the buyer.
To me art is not a means to an ends, it is an ends in itself. It is expression. The spirit(no I'm not getting religious or supernatural, it's a scientifically measurable thing) speaking out. I don't think any part of it is reliant on what other people have to say about it afterwards.
You raise some good points. The use of any subjective word, unfortunately, is unavoidable when talking about art. It is a judgment, and at the end of the day, "beauty is in the eye of the beholder."
But as I pointed out, there does have to be something to a piece of art or music that is appreciated by lots of people over several different generations and cultures. How is this even possible? Is it by chance that these same people like the same thing, or is there something more universal to the human experience that overrides our of individual tastes and personalities?
I totally agree that art is an expression. And it is uniquely human to express - no animals do this unless trained. And we do not live in a void - cultures all over the world are by their very definition groups of people, and our art can be and is enjoyed by one another.
When I play a song I've written for someone, I want them to love it. I want them to get the same enjoyment out of it that I do. When they do (and they don't always, sadly), then my joy in what I've done is heightened. I truly believe art is expression, but that it is also meant to be shared. Not everyone agrees, of course, but, hey, it's my opinion. :)