I disagree. I felt the language was very simple and easy to learn, and after the first exercise it was natural to use. Considering the course was very mathematical, the language was a perfect choice.
My impression was that the language was "too natural". I mean Octave notation is so similar to mathematical notation that many exercises could be solved by just typing a formula from lecture almost 1:1. Plus, learning Python and things like NumPy or Pandas would be beneficial on its own rights.
Also, IMO the implementation is not the core focus of the course. The key ideas are in the equations, and hopefully implementing them helps you understand the intuition behind those equations.