Since the technical task was locked in and first lines were drawn on the blueprint board, the Imperial Dropship was destined to face an impossible task: It had to carry up to 15 metric tons of payload, while being capable of low-orbit flight and also be armored enough to deploy personnel into an active warzone. 

Paradoxically, all of these tasks were fulfilled, but with a big caveat each:

The Imperial Dropship can not only lift up with 15 metric tones of cargo, but it can also carry a whole Standard Imperial Crate if needed. The problem is though – to achieve such impressive cargo capacity, ship’s whole cargo bay has to be detached by the crew of highly trained technicians and in such case the pilot would be literally trapped inside the cockpit… unless they want to take the emergency way out through the frontal landing gear.

Furthermore, the Dropship can transport soldiers and/or cargo down from the low orbit to the planetary service and then come back for more. Unfortunately, its engines are so inefficient and the fuel tank is so small that it can barely manage to perform 1.5 direct round trips before literally falling down from the sky out of the juice. This shortcoming was later mitigated with an additional fuel tank placed inside the cargo bay, but such praxis also came with risks to the crew of the ship who has to literally sit on top of an explosive barrel. 

Lastly, accounting for all above mentioned problems, the mandatory requirement for heavy armor made the engineering team literally cry. The resulting compromise between safety of the crew and aerial capability became pretty straightforward – since most dangers to the Dropship come from below, all of the armored plating is placed exclusively on the bottom side of the ship. The top on the other hand is literally made of paper-thin aluminum – just so that this penguin of a ship has any chance to fly at all.