I thought it was a good compromise to have them on the side on the first generation iMac, and the G4 could be swiveled to put them on the side as well. Even the G5, though it moved the ports to the back, still had them in a vertical row where your fingers naturally fall if you wrap your hands around the sides of the screen. I would've loved it if they'd kept ports on the side somehow but I'm sure somebody (Jobs? Ive?) thought it would look messy.