Everybody knows that you should use Rake tasks to run code from the CLI. But we also need to understand that Rake is more than just a part of Rails. It is an independent tool, and deserves consideration about whether it should be used or not. The main downside of Rake tasks is that they are hard to test – due to their DSL nature, they require special initialization. You should be very careful when putting business logic into Rake tasks. It is just as harmful as putting business logic into controllers in a web framework.
As with any tool, Rake is not limited to namespace, task and desc. You should learn how to use all of the benefits and functionality hidden inside. Try to look into the advanced Rake docs.
Also, we need to understand that there are much cleaner alternatives, like Thor. Thor provides the same simple functionality for writing your own CLI tools, but does so in a much cleaner, OOP way.