14 years ago we asked Leo Millions why we couldn't fly the RJ's at mainline. His answer was, "Even if we paid you the exact same rates, you still cost 30% more than they do, because of all the other benefits you get." (this was pre-9-11 and bankruptcy, when we still had a DB retirement plan, better, cheaper medical plan, etc.)
So, yeah, they've done the math, and it 'pays' them to keep whipsawing the regionals against each other to keep the cost of that feed at rock bottom prices. You need look no further than what Richard just did to Pinacle/Endevour to see what's coming re. regionals/feed, etc.
Offer their pilots a flow up to mainline and presto, cheap labor and a very cheap training pipeline. If they can't fill that pipeline, well, too bad, so sad, should have thought of that before you raped all the RJ pilots.
I'll bet Boomer and his buddies would have liked to have a flow up right about now.