What's the advantage of using this over the built-in GeneratePassword function in the system?
Simplicity, because with this action you just need to pass the length of the random string, you dont need to split the string from GeneratePassword, and with this RandomClass you have also an action that returns a random number between two numbers.
Why would I need to split the string from GeneratePassword?
Having the choice of number ranges sounds good. :)
Imagine that you need a string password of 4 digits length you need to do the substring not the split :D
with my action you send the length and it returns a random string of that length.