I've been called an affable curmudgeon by my comic book people. Those that look past how the message is being presented have come to understand that yes, there are things that have to be worked on in order for the work to be at a salable level. The curmudgeon part comes because I don't pull my punches. I'm hard on creators (including myself) because the public will be much harder. It's akin to high school: teenagers are purposely cruel.
People in general aren't confrontational. Creators are also a bit more temperamental because they are very close to their creations, and any rejection or criticism of the idea can be taken as a personal rejection or criticism. Because people in general aren't confrontational, they look for the easier way out of things. They don't want to hurt feelings because then they themselves feel bad. This leads to not telling the truth, and this is a disservice to the creator.
This is going to sound terrible, however, it needs to be said.
Your feelings aren't my responsibility.
You, as the creator, have a stake in what you've created. You're close to it, and being close, you may not be able to see the flaws. That's why you need to have an outside view (very often, the editor). The editor's job isn't to pat you on the head and tell you that you're great. They have a job to do, and that job is to publish salable books. If you have hurt feelings because you created a book that someone feels they can't sell, it isn't the fault of the editor. The only thing they did was tell you the truth from their perspective. If you can't handle that, that is still your responsibility, not theirs.
And this is why I'm often seen as an asshole. Not wrong, but an asshole. Because I don't take responsibility for someone else's feelings. I give truth, and sometimes that can be a harsh thing.
How you react to that truth… That responsibility is yours.