[atoav]

The airframe was changed significantly, creating the need for the whole MCAS solution — why? Because this was seen as a solution to avoid a recertification of the airframe, which would mean pilots had to re-train, which would mean airlines wouldn't buy, which means money would not flow.

Avoiding this recertification was the only reason MCAS was chosen instead of designing an airframe in such ways the now bigger engines actually have their center of gravity where it is expected to be.

This was ultimately a cost saving measure. Boeing could not be bothered to recertify the airframe purely for comercial reasons, not because it objectively made sense.

[WalterBright]

There is nothing wrong with making an airplane behave like the previous version. In fact, it enhances safety, as pilots can and do make errors when under stress they do the right thing for the wrong airplane. Making airplanes predictable and consistent with existing training is a safety enhancing practice.

I worked on the 757 design, which was designed concurrently with the 767. A lot of effort was made to make them behave in a common manner, even though they were quite different airplanes. This makes perfect sense.

It's the same reason the steering wheel and pedals on your car are laid out the same and do the same things across nearly all very diverse cars. And yes, carmakers adjust the handling characteristics to be predictable and not need the drivers to have additional training.

[kayfox]

Boeing had originally proposed a new small aircraft (with carbon fiber), but the airlines did not want this as it would have higher operations costs to have two different types of aircraft, so Boeing had to come up with a new 737, and the MAX was it.