"Also if the code was written entirely in C it will be easy to understand and debug it later on by other users"

Just as the mere act of writing in assembler does not of itself guarantee compact, fast code, neither does the use of 'C' in itself guarantee readability, understandability, maintainability, etc, etc. It is very easy indeed to write unreadable, incomprehensible, unmaintainable 'C'!
In fact, there is a whole website somewhere dedicated to "obfuscated 'C'", (the URL escapes me...)