I think the real issue is decision making experience and not just experience. I am in support of the 1500 rule for one major reason. It forces potential airline pilots to build hours doing meaningful flying I.E. instruction, freight, etc where they are forced to learn and make decisions. Gaining experience as an FO does very little in terms of learning decision making. The is a big difference in REAL experience between the guy who gets his certs with 250 hours and builds time working towards an ATP in a meaningful way verses the guy who goes right to an airline to be babysat for a few years. You need to learn to make decisions, and that happens when you are forced to make decisions rather than when you watch someone else make them while you fumble on the radios.
So in terms of the 2000+ hr pilots that have been mentioned on this thread keep in mind that its just a number. If we look at the breakdown we'd probably see that each of them had an unhealthy amount (too much) SIC time and not enough real, useful time.
The 1500 rule will force pilots to build time in meaningful ways. If you're not willing to spend a while instructing, hauling freight or doing any of the many crappy jobs we put up with to get to the top you don't belong at the top. Suck it up, learn to be PIC and send me your app once you've rightfully earned your ATP.
Did that make me sound opinionated?