I agree with you that the shareholders control public companies (mainly by the stock price). In a free market this would mean that the stock holders have indirectly indicated that it is best for Apple to give back cash instead of hoarding it because they feel Apple has no better investment they can make. IMO Apple has so much in cash reserves that if they tried to invest most of it they would be very loose and would make not so lucrative investments, so it may just be best that they return some of it back the way they are, and also invest some more in R&D.