>Your question only considers the take off situation. There are other occasions where it's nice to have two engines - flight over water or inhospitable terrain and/or night or IMC!<
Fireblob
This is my point. You loose an engine in the cruise and its no major deal to shut it down and fly for miles on the remaining engine the plane does not know whether its at 4000 feet or 400 feet and behaves roughly the same.
But the same plane asked to climb? and you are in a totally different ball game.
Pace