They should have put the new engines on a new airframe with more ground clearance under the wings, that would not have required the heavy engines to be pushed f

They should have put the new engines on a new airframe with more ground clearance under the wings, that would not have required the heavy engines to be pushed forward and change the center of gravity in order to fit. Such an aircraft would no longer be considered a 737 for the purposes of pilot certification. The whole thing was motivated by that. Pretend it's the same plane, so that the pilots can pretend to know how to fly it. It's analogous to hiring a Java or C# applications software developer when your codebase is actually in a proprietary variant of C++. It's close enough that they think they can code in it, but no one ever mentioned how the memory management subsystem is actually just a library written by Dave, who left the company in 2004, and if you aren't careful to clean up your references correctly (according to Dave), the biweekly analysis run will crash-to-desktop in the 14th hour, and you will be called by a panicked twentysomething at 5 AM on a Saturday. Then you find out about the custom compiler (also Dave), and start sending out resumes before it's too late. But with pilots, there's no one else to send the resume to.