I see your point, but IMO if we go that route we can basically claim that if every player could eliminate their weaknesses, they would be the greatest (rendering this thread moot). Personally, Shaq's ty FT shooting and other basketball flaws are a reasonable tradeoff considering what he brought, well for anyone who isn't superhuman. Similary, if Dirk became a great defender and an elite rebounder (can argue he was in the playoffs), he'd probably be the most complete player in history.
My beef with Shaq has to do more with him being lazy, not caring for his body as he should have, and his personality/conflict issues that broke up a dynasty. He has four rings, so he definately isn't a failure by any means. But personally I think he had the tools to at least be remembered as the greatest center of all-time over Kareem and Wilt.