This is a tradeoff due to mission priorities. Embedded nacelles (as in fighters) reduce drag (the point of this project is to increase efficiency), but complica

This is a tradeoff due to mission priorities. Embedded nacelles (as in fighters) reduce drag (the point of this project is to increase efficiency), but complicate matters of structural support and increase engine vulnerability in case of fire. These have superior shielding to runway debris and birdstrikes, but such incidents are extremely rare.