When I did my PPL many years ago spinning was part of the syllabus, and I think that it should have stayed in.
As an instructor today, I encourage all my students to spin, as it gives them an invaluable insight into the handling characterisitcs of the a/c and I have found that those students who opt to spin develop more confidence in the a/c and their GH skills show a distinct improvement.
Providing the exercise is carried out in an approved a/c and all the relevant safety checks are completed, there is no reason why spinning can't be demonstrated....