Although Leo Mullin was an idiot who's negligence nearly killed Delta, I will agree with his general point that big airplanes should pay much more than they do ... unfortunately ... the converse is also true ... there should not be as many 50 seat Captains making $120,000 to $150,000 a year.
It has long been my point that if you distribute pay along a productivity curve it would make sense to redistribute pay upwards from the RJ's; if the RJ's were captured at mainline. But, as separate entities with nontransferable longevity they negotiate the most they can get.
Consider that more than a handful of Delta pilots took a $100,000 a year pay cut to start over here. IMHO capturing that flying even at reduced rates is preferable to the loss of a pilot's longevity mid career.