AA toyed with the idea when they were flying the F100....they even wanted / talked about the AA guys flying the F70....... plain and simple the mainline pilots wouldnt fly the F70 for the what company wanted....and the company didnt think they could fly it profitably for what the pilots wanted thus the BLOSSOM of regional jets. In those days AE flew NO jets ... the ATR-42 and a few 72's were the only big things they had.... Jetstreams, shorts 360's.... saabs.... for the most part the mainline #of seats per acft has increased and it certainly has increased at so called regional airlines....