I've just recently started singing lessons and at the end of the lesson my teacher apologised for stopping me and correcting all the little things I was doing wrong. She explained that she thought I was good, and that meant she had to push me to do my best.
This is like writing (in some twisted, far-stretched way). No one likes getting criticism, especially that of the negative variety, but why would someone go to the trouble of pointing out any areas that might be a bit flat (sorry about the singing pun, I couldn't help myself)?
Lets face it, if they didn't feel the work was good, they wouldn't want to waste the time to read and critique the work (especially 2,000 word chapters and 80,000 word novels). So, it's good to think of critiques in a positive way. They're just trying to push your story (and you) from being good to being great.
How do you look at criticism? Do you accept it and try to initiate the changes suggested? Or, are you scared of letting others get a hold of your work in case they say some negative things you don't want to hear?