23 years ago the regional level was... US Air (ok Piedmont) and Eastern Air Lines. (At least in Florida where I grew up... In Texas it was WN and Texas Int'l.) Sixty seat jets were Fokker F28s and DC-9s. The routes were intra-state. In other words, regional flying.
One problem with experience in the cockpit is scope. No one wants to stay at Colgan, and few at a top shelf regional, simply because the brighter future is elsewhere. So the most experienced pilots there still ougt to be sitting in the right seat. The right seat of bigger equipment certainly. If all flights sold by CAL were operated by its own pilots, chances are better that a more experienced pilot would have been PIC that night. And the Colgan Captain would have been happy to be a 737 FO.
I tend to agree that an ATP ought to be the minimum requirement for passenger carrying under 121. But far more important is a stable environment where those with the most experience can pass it on to those who need it.
"You need someone older an wiser
Telling you what to do
I am seventeen going on eighteen
I'll take care of you"