David Robinson is pretty much a casualty of his own success. If he actually sucked in his prime a little more, management would have been under more pressure to bring in some decent help outside of Vinny Del Negro and Avery Johnson. Do I think Robinson > KAJ, Duncan, Magic and Bird, absolutely not. Could he have been? Yes, with the right team, he could be very successful. Put him on a team in place of Dirk Nowitzki on the 06 to 11 Mavs, the Mavs would have won at least 1 championship, perhaps two.
As for Magic and Bird, the game admittedly, is different back in the 80s. Talent was way more concentrated on a few teams, and a team can only win so many games, so the WS are split between the players. When a Bird or Magic is not on the floor on their respective teams, they don't suffer as much, because there are the Worthys, McHales, Parishes and KAJs to keep the game close.
KAJ on the other hand, had his prime prior to 77. As much as Laker fans like to say he was the best Laker ever, his prime years were with the Bucks.