The Unlikeable Protagonist

In fiction, it's important that the reader identify strongly with the main character, as often the main character is the reader's only window into the world of the story. Ideally, the reader should be lost in the world of the story and not be aware that she is reading the story, but instead feels she is living it. I have heard it argued that the only way this can be done is if the reader places herself in the role of the main character.

That sounds logical, as far as it goes. An extension of this viewpoint, however, is that if the protagonist is someone the reader would not like to be, then the reader will jump out of the story and never let herself experience it. This, obviously, is a problem. What if, on the other hand, your character starts out as someone unlikeable, but through the events of the story changes his ways? Scrooge in A Christmas Carol is the obvious prototypical example of this.

Is Scrooge the exception, rather than the rule? I tried this approach once with a story I wrote for a workshop I particpated in. The protagonist had, before the story takes place, caused an accident that killed a large number of people. Because he was unable to forgive himself, he turns inward and decides never to interact with others on a personal level again. While he's no villain like Scrooge, he's not terribly nice to those around him. Events in the story, however, make him realize that he can't live without other people. He finally overcomes his guilt and begins to rebuild his life and relationships.

The story was very well received in the workshop, but the instructor (a past president of Science Fiction and Fantasy Writers of America, so she presumably knows her stuff), said that while she loved the story as a whole, the fact that the protagonist was an unlikeable character throughout much of the story totally killed it for her. She suggested I tell the same story from the point of view of another character, who ends up being instrumental in helping the protagonist work through his problems. I haven't done that yet, but probably will in the near future, just because I'm curious if it will work.

So I'm wondering: Is there no case in which an unlikeable protagonist can work? Scrooge may in fact be a mutant exception, and frankly, I've never bought the transformation that comes over him at the end. He wants to die surrounded by friends instead of all alone, so he changes his whole life? Not bloody likely. Odds are that if he really doesn't like people (and we see no evidence whatsoever in the story that he does), then he's not really going to care what people think of him when he's dead.

Can it work? Or is this one of those hard-and-fast rules of fiction that is just so tied up in our psychology that we can't break past it?