http://www.economist.com/blogs/gulliver/2012/10/virgin-ameri...
"If you want to be a millionaire, start with a billion dollars and launch a new airline." -- Richard Branson
All in all, it's a tough industry. That said, you get a few new entrants every decade. Frontier ('94), Jetblue ('2001?), Virgin America (2007).
I'm sure one of them has tried being nicer to customers, but next time those customers went to buy a ticket they bought one on AA cause it was $10 cheaper or left 30 min later.
Someone did a focus group awhile back about all the nice things an airline could do. And everyone was really excited about all the niceties that were on offer.
But then they asked everyone to raise their hands and to pull them down once they were no longer willing to pay that much.
At around $30 extra, over half the people had put down their hands. At $50, all but one.
For whatever reason, people de facto hate paying trivial amounts extra even in exchange for significant improvements. That's why we end up with really shitty flight experiences.
EDIT: Corrected spelling
There's some areas in the higher end stuff, but right now JetBlue / Southwest are about as progressive as you get.
I read an interesting blurb somewhere recently (forget where, sorry) that pointed out that it doesn't actually take that much capital to start and run a (small) airline. You can lease a plane and start out serving only one route, and you've got yourself an airline. Of course, how much capital is "a lot" is relative... let's just say that I won't be starting an airline anytime soon. But still, apparently it's easier to break into that business that you might think, looking at it from the outside.
It's not like alot of smart people haven't' tried. The airline industry is littered with the corpses of failed companies.