Originally Posted by Larry in TN

That's right, except it isn't Boeing making the decisions.

Boeing and Airbus are in regular contact with their customs, airlines and leasing companies. They discuss possible designs and what the airline might be interested in buying. The MAX line was built because that's what Boeing's customers wanted at the time. They wanted a more efficient airplane, sooner, at lower cost, and with training commonality, which a clean-sheet design wouldn't provide. If Boeing didn't deliver, most of those MAX orders would have gone to Airbus.