Well, they had to choose the use of one of the endian representation schemes because numerical data needs to be stored and manipulated in its binary form in the blockchain one way or another.

This comes from the fact that digital cryptography used in chain usually operates on the data in the bit level (binary form), so programmers needs to be aware of what kind of representation/storage scheme is being used so they can write algorithms that correctly manipulate the data.

Hope it helped!