Judges are just human. I've judged sewing shows and county fairs. If a judge doesn't write enough, people are upset. They want to know how to improve their work. If a judge puts too much people think they are being picked on. And every judge has their own ideas about what and how something should look. It sounds like this judge thought a quilt should have more dense quilting and kept that standard the same for all the quilts. Another judge might think there was too much quilting. At least the judge was consistent.
Judging is not as easy as most think it would be. As someone else said, they have to find things wrong in order to decide which item should be marked as 'best'. Which 'wrong' thing is worse than another 'wrong' thing? The audience needs to feel that the one selected as 'best' is reasonable as well. Sometimes the reason one quilt ranked higher than another is because of something that isn't glaringly obvious.
Don't let this experience stop you from entering another judged event. Every experience is a learning one and your quilt is a loved one. Isn't that the reason we all quilt? We want a loved item that will give warmth and comfort. Every quilt is a winner when that criteria is remembered.