Twins are just ... COOL. Hard to justify it any other way. You add a new level of complexity, things to go wrong that really outweighs the benefit of being able to maintain flight on 1 engine.

Just like on full scale aircraft you will always have a critical engine. It is the one that is still running! And if you are not prepared for the asymmetrical thrust and change in handling it will be the one that will lead you to the scene of the crash.

But twins really are just plain ... COOL.