-11 is NOT old and antiquated. If it takes 186,000 lbs of thrust to propel a 3-holer.....then it would take exactly 186,000 lbs to drive the same plane as a 2-holer. 2 bigger engines or 3 smaller ones, what's the difference other than the numerical count of engines? Having three leaves more options if one fails. It all comes out in the wash.
The only reason 2 engines clone planes are so popular is the same reason SUV
's are popular.....because that is the current sales pitch. Everyone wants, no demands, everything to be bigger and bigger every year. Who wants those teeny weeny engines when you can have the bright shiny new mega monsters that barely fit under a wing. Look at the 777 and the 380....need I say more?