Most of the discussion seems to ignore the "in this space" (scripting existing software packages) part of your question.
I submit that Python is more popular in this space because:
- many end users will be users of the package first, and programmers very much second. In this case a very gentle learning curve is more important than ultimate expressivity for hackers.
- In the same vein, it superficially looks more like BASIC than Ruby does
- The C API may be simpler to use than the Ruby interpreter, though never having used Ruby's C API that's speculation on my part. Never understimate implementor laziness as a technical driver.
I submit that Python is more popular in this space because:
- many end users will be users of the package first, and programmers very much second. In this case a very gentle learning curve is more important than ultimate expressivity for hackers.
- In the same vein, it superficially looks more like BASIC than Ruby does
- The C API may be simpler to use than the Ruby interpreter, though never having used Ruby's C API that's speculation on my part. Never understimate implementor laziness as a technical driver.