I don't know if anyone brought this up. I wished that UA had introduced a hybrid system. 5 miles per dollar for all economy fares except refundable fares and 6 miles per dollar for all other fares, plus bonus (25 to 100%) based on your status.
This does not penalize those who buy higher dollar fares and at the same time the elites get their bonuses. This would a good hybrid and does not follow DL blindly.