Apoorva's blog post on functional programming in R touches on some really important pointers on why, as data scientists, we might want to level-up our programming skills. Here's some highlights:

However, as you take on increasingly complex projects, you may find yourself thinking about more and more about structuring your project well and writing code that is easy to understand, debug, reuse, and maintain.

And:

By applying some basic concepts of functional programming, we gain:

• better maintainability of the code base;
• safer and reliable code;
• the ability to manage complexity with abstractions that are borderline wizardry.