I know - let's remake "Casablanca"!

Just finished watching "The Flight of the Phoenix" - the new one that is. Not bad, not bad at all, but what kept running through my mind was - why did they bother? The original was and still is a classic. The new one really adds nothing to it, so WHY? When you think about it, all the remakes are of successful films, whereas logic suggests that if you're going to remake a film, you should look to a previously unsuccessful film with potential, otherwise what's the point? Perhaps the point is that people who remember the original will go and see the remake out of curiosity as much as anything - in other words you're trading on the success of the original to make money. Or am I just being cynical again?