I don't believe in objectivity. It's not a matter of being "conditional" on too many factors: I think there's no "objective reality" to consider when talking about art.

The artistic work in itself is not what we call "art": art is the complex of personal, cultural, historical perceivings the work stimulates. There's no way but complete arbitrariness to estabilish the parameters one should use to "judge" an artistic work.
Structural, cultural, historical parameters may seem quite "objective", but they reflect the arbitrary assumption that, since there has to be an objective artistic value, then there should be objective parameters to determinate it.
Furthermore, art is not history of art, and adopting categories such as "innovation" or "influence" completely shifts the layer of discussion.

So I think artistic works don't have any kind of "intrinsic" value. There is, nonetheless, a privileged viewpoint to consider a work: the one from which that work can be understood, appreciated, loved. Fans and those who love apparently mediocre works are always right, in my opinion.
My ratings just explicit my closeness to the "privileged viewpoint" for musical works I listen to. The higher the rating, the closer I am.

I don't rate classical works, because RYM organization for classical music sucks.