Other than ripping cds and dvds, I haven't used an optical drive in years. And given that most people buy their music online and don't rip their movies, I don't see it's really that out of the question that they don't do optical drives anymore. You could have made the same argument about the need for floppies when apple abandoned them, too.
And it's not just apple's optical drives that are crap. Any laptop drive (which is the form factor for a device like the imac) isn't going to stand up to heavy duty ripping duties.