It has some flaws. Reading Lolita in Tehran is a good book, but the argument that The Great Gatsby makes people more sympathetic to others rather founders on the way it doesn't make people more sympathetic to Tom and Daisy Buchanan. There's many a work that assassinates some characters in order to make others look more sympathetic.
And there's the little problem that the readers who most need to be taken out of themselves are the least likely to be affected, who will merely sniff at the work. It's not limited to characters, actually. Readers obsessed with the current day and with issues of the moment could in theory benefit from works where the setting doesn't contain any such issues. It could cool them and give them some perspective -- but those readers will then dismiss the work as intrinsically popcorn and fluff exactly because it escapes their hothouse world. You get it with characters too, although there the dismissal is that the character is implausible, and the reader can't believe that a person would act like that. Some characters do act implausibly in some books, which is what makes it hard to judge, but it's so easy to reject the mind-broadening as implausible.
I could go into the moral side of it since I've read many readers rejecting good characters as too good. I could quote Aristotle on how we want characters to be about as good as we are, or a little better, and while by "good" he included more forms of goodness than the moral, he did include the moral. I could quote C. S. Lewis: "Good characters in fiction are the very devil. Not because most authors have little material to make them of. But because we as readers have a strong subconscious wish to find them incredible. "
But that could easily get rude, so I won't. 0:)