I'm not sure that there are any critical views that go beyond someone's aesthetics. *shrugs* It's a potential debate. That said, people who write and critique on a regular basis often have some idea as to what makes a story potentially more commercially successful/interesting to the average reader, etc. (Not always, but often. After a point, you really do learn to spot flaws like, "I think this dragged a bit here because..." etc.)

If you're serious about writing (i.e. want to publish), I'd definitely suggest finding a good critique group. While some authors have done fine without one, in general, there's nothing like having people around to explain where things are/aren't working in the story to help you genuinely grow and improve.