Northwest is the strongest of the major USA Airlines
Perhaps you want to be a lifetime million miler of Eastern, TWA, or U S Airways?
Many of the US airlines are in deep financial trouble and probably will not be around in the long term.
Northwest is being cautious, conservative and trying to avoid going bankrupt.
If you own a business or are in sales or management you realize "What have you done for me today?" is a reality. You can't allocate a lot of resources for inactive business relations.
I think if you look a little deeper at Northwest, you'll find that they are a well managed airline.
RC