Why are the engines of 737NG are flat from the bottom?

Earlier in the 1960’s, the Boeing company was thinking about manufacturing an aircraft that was relatively easy to use for the ground handling companies and cargo agents. Back then, the ground handling companies were using a procedure called “Bulk Loading” where they would just literally throw the baggage into the hole and they weren’t using the containers like the ones used in the modern airport operations. Due to this, Boeing wanted to create an aircraft which was lower to the ground.

Fig 1.1 - Flat Bottom (The Engines are actually round but the lid is flat from the bottom)

Since the 737NG is a stretched-out form of the initial 737 model introduced by Boeing, the engines had to be mounted on the wings in such a way that it would balance the Center of Gravity which was shifted because of the now stretched fuselage of the aircraft. So, Boeing redesigned the engine pylons in such a way that the engine was not under the wings, but they were ahead of the wings and they were lifted from the ground.

Fig 1.2 - Engine Pylons

It also helps in the crosswind landing because, in crosswind landings, there is a chance that the engines might hit the ground because the aircraft is built with a landing gear which has a lower height than others. The flat bottom helps eliminate the caution of the engines hit the ground during crosswind landings.

Fig 1.3 - Bulky sides of the engines.

One can also notice the bulky sides of the engines of the 737NG, this is because the engine manufacturing company (CFM international) moved the accessory gearbox and the fuel pump from under the engine to the side of the engine, which is why we can notice the unusual shape of the engines from the side.

PS: Feel free to correct me if you feel like I have said something wrong, Credits to Pilots (do check out their youtube page for more)