Being able to write code, even if badly, is tremendously helpful if you want to study cryptographic (or many other) mathematical algorithms.

I know it's kinda stating the obvious but people with a preference for pure vs applied mathematics, they often feel a bit "sniffy" about bothering to actually write code. Whereas in fact, actually writing code that executes what you *think* is true or possible, very often illustrates flaws in your reasoning.