Hello:
That design of the door is because of the space the wheel need to go up and down without get stuck. If you go to the emergency and abnormal procedures section of the flight manual, Main Landing gear Extension After Normal and Emergency System Failure, one note say this: Extend the Aft strut firt. The main landing gear doors are opened by a mechanical connection to the aft strut, and damage to the doors could result if the forward strut is extended firt.
If the door don't have that shape the wheel would get stuck.