I hate to tell you this, it isn't NW, it is DL management in an effort to save money and scare the heck out of their "NEW" NW employees.
Wait til you find out about PASSENGER PROFILING unless you are Platinum Elite or Platinum Medallion, your fun days of free upgrades are over - big time - I know from experience.
More here on a photoblog I posted about all of these changes:
http://www.flickr.com/photos/kmemav8r/3669154291
and more on deceptive booking codes like 75N and 32R here:
http://www.flickr.com/photos/kmemav8r/3274340949
Quite frankly, Delta ruined their own once "Good Name" with this merger.
My only hope is that the Capital Equipment merger gets held up forcing NW to serve DL.
Passengers, employees and investors have never been so deceived by one company - DL livery is the only nice thing I can say about them.
After telling me I could buy my confiscated miles back from DL (over $6000), I knew it was time to go back to another carrier.
Here is one way you can get some "free insurance" book via Alaska and if you have probs with DL or NW and AS issued your ticket, they can reroute you (and you may find a whole new way to travel in certain markets:
http://www.flickr.com/photos/kmemav8r/3535896580