There is in every aspect of life a continuum, and we all fit on it somewhere. I once read an article that told of asking people where they fit on the range between ugly and beautiful. Most felt they were on the plus side of center, and yet on any scale, 50% have to be below and 50 above. So a bunch of homely people are deluding themselves about how scary they look.
I suspect it's true for writers as well. I've never met anyone in the business who admitted to being a below-average writer. Even the self-published folks who have spelling errors on the first page defend their work as "pretty interesting stuff." It's been said before, our books are our children and nobody thinks his baby is ugly.
Like our babies, our books reflect us, so if we admit they have faults, then we might be admitting that we have them. Recent posts in one of my chat groups have been from those who edit for pay, and their main complaint is that people don't take criticism well. If you say you don't like my nose, what am I supposed to do about it? That's true for a book, too, at least for many. They can't change their work without making major changes to who they are, and many aren't willing or even able to do that.
I think a major plus for a writer is recognizing where she fits in the spectrum. If you can say to yourself, "I am not the next Ernest Hemingway", that's good. If you can admit you aren't the next Clive Cussler, Rosemary Rodgers, or Sue Grafton, that's good too. Recognizing your place in the spectrum saves you from making absurd claims in your query letters ("I'm the next Dan Brown"), from refusing to grow ("This is the way I wrote it, and this is how it will stay") and from embarrassing yourself at conferences ("My book is so funny you'll laugh out loud. I guarantee it.")
There's always somebody whose book/baby is prettier than yours, and of course, there's one that's uglier, too. As long as you're willing to admit that, you can take your place on the continuum and maybe even move toward beautiful.