How ridiculous. You have to buy an Adobe product to simply rotate a document. Seriously Adobe!!!
Why does you assume this?
It's almost as if Adobe are in business to make money.
You can rotate the view of a PDF file when you use the free Reader, but you can't save that change, as that would edit the document, which Reader can't do. Yes, you need to pay for Acrobat (or the Edit PDF online service) to do it, or use non-Adobe software.