I think that if you're just writing a script to solve a math problem or automate a task, there isn't really a strong argument as to whether you should use Ruby, Python, bash any other high level language. You should probably use whatever you're most comfortable with.
But if you're making an application with a database, RoR is an extremely powerful tool. And this isn't just a case of Ruby having the best library (in the same way that Python has the best scientific computing library). It's a case of the library functionality and the language playing together really well.
Ruby statements look more like natural language statements than those in other languages. This is a really helpful design choice when you're building a crud application. In that context, you're not thinking about X, Y, -Log(X + Y) or whatever.
You're thinking about a new customer, or whether some old customer is a member? of some mailing list, etc
In a weird way, it's similar to how Haskell users love the fact that statements in Haskell are mathematical truths. In the case of logic programming this is a handy feature to have. In the case of writing the business logic of a CRUD app, it's handy if your statements look like natural language statements about the underlying real world objects whose representation you are reasoning about.