Well you have to put the Lakers in context... the Bulls never had any "real" point guard either, but the one thing both teams have in common is that they had GREAT combo guards(#1 and #2 all time) in Jordan and Kobe. And not only that, they had some of the best passing forwards in the league(Odom, Pippen) who were extremely versatile and could do anything on a basketball court...
Now, when Kobe had Shaq, no, they didn't have any "real" point guards or point forwards for that matter, which is exactly why his assist totals then were higher than they are now.
There are positions that are more important than others as far as what the players do from it... as evidenced by most teams winning championships with dominant big men on both sides of the floor(or being AMAZING on one side), but a great coach is a coach that is able to negate a weakness in his team(like Phil Jackson with his lack of PG's) and turn it into an advantage(running large players at the point to create mismatches). That's basically what Phil's triangle is all about... mismatches.
As far as the actual question, I would say the center position is the most important because of his ability to control an entire game by slowing its tempo. Having a great center leads to less fastbreaks for the other team(because most shots are close to the basket), less easy baskets at the bucket, and a high percentage offense 'cuz of the defense needing to double down, allowing the Center to hit the open man and initiate the swinging of the ball...
Look what Olajuwon was able to do with a lack of talent(old Clyde Drexler, Sam Cassell, and Robert Horry... you kidding?!) or what Kevin Garnett did with the Celtics this year(if he isn't on that team, they probably win 30-40 games), or what Greg Oden will do for the Blazers this year(they're a playoff team, mark my words), or what Ewing brought to the Knicks(who also weren't TOO talented in my mind), or what Robinson brought to the Spurs', or what Duncan has been bringing to the Spurs'(championships) for the past 9 years... Being able to dominate a game through a post is instrumental in building a dynasty, unless your players are UNREAL and are not "dime a dozen," ala Jordan, Kobe, Pippen... I guess you could throw Centers in the "not dime a dozen" lot too...