Errr......
Centre of lift / centre of gravity considerations.
those engines are heavy 'mothers',
Cheers
True, but remember that this design philosophy emerged in the 707 days. A JT3 weighs less than a CF6 does, and obviously worst case scenario from the designers point of view would be one leaving, not the whole lot (experience has taught us different opinions since then). In such a case the CofG would move aft but not by so much to make an emergency landing impossible.
And with the then available knowledge of jet engine reliability and behaviour when misbehaving the standpoint "I don't want that on my airplane anymore" would perhaps have its merits.