I can't believe I read this whole thread....

Major obvious points:

You can be a great pilot with low time, and you can be an awful pilot with high time. As the old saying goes, are you a 1,500-hour pilot, or a 1-hour pilot 1,500 times? That said, as with anything, more experience is usually helpful. We see this all the time in many different scenarios. Also, just because it's theoretically possible to be a safe and competent low-time airline pilot, that doesn't mean it's the best way of doing things.

Sure, more experience might not always correlate to a safer pilot. As a CFI, I have my fair share of horror stories from flying with old high-time rich guys who were terrifying. However, as a general rule, more experience is better.

I feel sorry for the people who have jumped straight from the 172 training mill to the 121 world, without actually ever experiencing the world of aviation. My second CFI job was at a museum, teaching high-school volunteers in a fleet of vintage airplanes. It was also my first tailwheel experience. I'll tell you, I got into that Champ a commercial pilot and CFI who thought I knew how to fly anything, and I got out of it completely humbled. Hand-propping builds character.

Second point:
Supply and demand. We all complain about the lack of pay and working conditions. For that reason alone, I would support that all 121 crew-members should hold an ATP. Reduce the number of qualified applicants, and employers will be forced to do something other than drop their minimums in order to staff their flying. This is the reason our industry is frustrating. Is 20k/year flying a CRJ really all that better than 20k/year being a CFI and being home every night?

And to be perfectly honest, I see it as fixing a loophole that's been around for far too long. In order to fly as a required crew-member on a Transport-category airliner, you should hold the appropriate certificate. I'll give you a hint, it has "Transport" and "Airline" in the name.