The working premise of Airline Deregulation was that it would stimulate competition and that that would be good for us, the consumers. Airlines would lower rates, improve service, fly to more locations at more times, etc. There was a brief period in there when it sure felt like that was happening. Then again, any airline can lower rates and give you more if they're operating at a loss. They just can't do it forever.
Here's an article with charts to show how competition has declined. If you presume more competitors in the field equals better values and service, you have to admit we're not getting it as more and more airlines either close down or merge into others.