I do not disagree with you! For example the book http://faculty.luther.edu/~macdonal/laga/ gives an elementary introduction to the subject.

I have learnt about geometric algebra just this year, and applied it to compute the graphics in an app I wrote for a customer. It was a real eye opener, concepts that I struggled with before were really simplified by using geometric algebra.

BUT: I would never have guessed the usefulness of it for me from this paper.