[T]here should be a small part of every critic, I believe, that grieves quietly each time a creative product is less than it ought to be. Every so-so TV series, every half-baked movie or underachieving book [or less-than-satisfactory play or musical--mine] is a lost opportunity. To be sure, a critic's job is to point out just how and why the entity in question falls short. Yet if you don't find yourself ever-so-slightly saddened by the gap between what is and what might have been, you might want to feel around and make sure you still possess a soul.
-- Julia Keller, “Big Meanies: On the Writing of Negative Reviews,” in the Chicago Tribune