Re: Is it a good idea ...?
Bolting engines onto an airframe that was never designed to cope with said engines
This is the bit I never understood. The ground clearance was already marginal in the previous generation (witness the odd-shaped engine intake cowls) so wouldn't any sane company have been looking at that compromise as a stop-gap, and furiously redesigning the aircraft to take the larger engines which would obviously become available in the future, or perhaps designing a completely new aircraft in that capacity / range bracket?
The stated reason at the time was to maintain compatibility with existing airport infrastructure - something to do with door heights - but is that really a problem?
From a layman's point of view, sticking the engines forward of the wing and unbalancing the aircraft is only marginally less radical than bolting them to the back and flipping the tail upside-down.
Whatever happened to the MD-90 / 717?