They don't bother me, but I don't read them. I know some people like them, they're supposed to add history and nuance to the atmosphere of the world and such, but I don't read them. Also, when characters burst into song or poetry within the narrative, I skip past that with an eyeroll and look for the restart of the narrative. (See: The Hobbit).
Yep, that's right, a book I've read at least 7 times and I've skipped past the singing nonsense every time.
Now, at the beginning of a book, I'll entertain quotes. Stephen King comes to mind when I think of this...the man likes to put quotes in front of his stories. But the location of those quotes don't interrupt the narrative.