WHat if you broke your cd or dvd... ? <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />
Then you're screwed...but a dongle would be just another thing to break, or lose in addition to your cd/dvd, thus multiplying the lose/breakage by a factor of 2...see I thought about that!! <img src="/ubbthreads/images/graemlins/biggrin.gif" alt="" /> <img src="/ubbthreads/images/graemlins/winkwink.gif" alt="" />.
Plus you'd probably be paying for that extra 'hardware' cost for them to make those things.