Why do we want more clutter on the desk? It's a desktop; leave it in. My MBA doesn't have an optical drive for good reason. The iMac does not need to be thinner or lighter.
Clutter is not the point of this debate. The point is the technology is still commercially available and accessible to those who need it.
Somehow I seriously doubt Apple doesn't think about thinness and lightness in all of its product lines.