Maintainability: It's easier to maintain code when it's broken into smaller, more manageable pieces. 

Readability: Code is easier to read when it's separated into distinct functions. 

Reusability: Well-written modules can be reused in other projects. 

Scalability: It's easier to scale systems when they're broken into smaller modules. 

Testing: It's easier to test code when it's broken into smaller, singular-function modules.