I love the Classics too, but I appear to be in the minority who think that the 2005 King Kong was even better than the 1933 original.
For the record, I also think the 1982 The Thing is better than the 1951 The Thing From Another World.
Having said that, most remakes are indeed not worth the time. The Day the Earth Stood Still comes to mind. Cat People comes to mind. The War of the Worlds comes to mind.
Harvey (1950) has a great performance from a great actor. Let me remind everybody that Harvey is not a rabbit, he is a Pooka. As such, he is real, but invisible to everyone except one person.
Will SS mess up the story? Probably not. He has a good track record, and Harvey had a very long successfull run on broadway before becoming a film, if we EVER see more of Harvey than his shadow, the impact would be lost.
Remakes should not ever happen because somebody believes that the present day technology of movie making allows you to tell the story more convincingly - down that path lies all the truly horrible SyFy channel low-budget films, lacking even the spirit of the 1950's "B" movies. Remakes should only happen when you have a cast that can match and surpass the original. I have a very short list of male actors who could equal or better James Stewart, and Tom Cruise is not on it.
As for the reason for remaking a film, that is because if a film made money once, it will do so again, meaning that in tough times, a remake is a better place to invest money. Because one thing in Hollywood has been true forever, and that is that there are few true artists and a lot of hacks in the place. I believe it is better to make a GOOD remake of a classic than to make a bad version of an original film, because "original" does NOT mean "entertaining".