Bogus arguments
The arguement for twins is (almost always bogus).
The increased risk of running (and carrying) two engines needs to be less than the probability of an event occuring where having two engines might help.
The small slivers of time when having two engines might help rarely justify the risks.
Just curious - but what does happen when all power fails in a twin ( fuel, drive system etc )?
How do people expect the driver to land this heavy brick - the pilots are not trained for it (no EOL in twins) and the machine does not do it very well !! In a single (generally more reliable) the pilot can land uneventfully in most cases.
1 minute per hour certainly would not justify having a twin!
....and many other points (European protectionism, jobs for the boyz etc)