"Why is this here?"

When you write, having other people look over your work is critical. Provided you have some desire to get your work published, it’s important to know how it’ll be perceived by minds other than your own. It’s important to keep a bit of distance between yourself and the work at this point in the process, because some of the questions and comments made might seem harsh. However, they’re ultimately going to make the work better.
Case in point.
My wife was reading something I wrote last night. She commented on some of the things she liked, but one question she asked caught me off-guard: “Why is this in here?” She was referring to a particular character, and what I noticed more than the question was my response. It took me a long time to formulate one. A long time. Like, a minute or two.
And even as I was telling her my rather weak justification, I realized what she had found.
A darling.
Now, I didn’t Mozambique Drill the thing right away. So I have a darling here, I told myself. What do I do with it? How can I take something that goes against the impetus I had for writing what I wrote in the first place, and mold it into something better? It’s something I’m still chewing on. But I wouldn’t have noticed it without the critique.
Entertain those questions you’re asked by your readers, don’t dismiss them out of hand. Think about what your writing, especially after you’ve written it. The end result of the work will be much more favorable.