As any subject to learn, you don't have to if you don't want to. More seriously, as in programmation, many new languages manage memory with a garbage collector

As any subject to learn, you don't have to if you don't want to. More seriously, as in programmation, many new languages manage memory with a garbage collector or other mechanisms, but if you want to be a good developer, you need to know how all this is done underneath. To drive a car, you don't need to know how an engine works, but to create one... And for the particular subject, you have to understand the principles under your tools to know how to change parameters and understand why the tools can be biased with bad parameters (or not enough data).