If I think that an album is good because I made it and I feel like I did a really good job, and someone else thinks it's no good because it's “nothing special” or “run of the mill”, who's “right”?

I say both of you are, because art can only really be evaluated subjectively, based on an individual's personal context.

in music, in comics, in probably all venues of creativity, there is more good quality work being done than we usually recognize

Alternately, you could say that, for any given person, there is an enormous body of artistic work available that that person hasn't really considered, yet would appreciate.

maybe we are too quick to condemn something for not being arrestingly exceptional or The Best

Or we simply don't know it exists at all. In pop culture, as in technology and business, there is a tendency for people to artificially limit their options -- to converge on a small handful of any given class of offering.

Only those few, after a certain point in time, will enjoy any real promotion or widespread appreciation or brand strength. It isn't about actual competitive merit.