I moved your post into the existing thread on this topic. Scroll back and you will find many of your points discussed by other posters.
Originally Posted by
Roswell Dawg
....it seems like what they are selling you is some sort of second-class ticket. The airlines are unable to change the ticket because its part of some separate inventory.
This is true of tickets purchased through
any Online Travel Agency, and varies by airline. Delta, for example, will often allow agency tickets to be changed on delta.com, but other airlines may not. Changes then need to be made through the agency.