If you don't think MJ is a much better shooter than LBJ then you must be too young to remember MJ. Or either you're just dumb and you probably think LBJ is a better shooter than Kobe or Carmelo also, but he isn't close to having that kind of consistent jumper no matter how high his shooting % is.
Jordan didn't really have 3 point range, but was a great mid range jump shooter with great touch and a natural stroke. To me he's a better shooter w/ a quicker release than Kobe, but Kobe just has more range. MJ's free throw % is 10 points higher than LBJ's.
LBJ's shooting % is so high because he can't be stopped at getting to the rim either in half court sets or in transition. He's very efficient on offense because he takes great shots and overpowers people to get to the rim, but that doesn't make him nearly as skilled of a shooter or dynamic scorer than MJ or Kobe.
Once LBJ doesn't have the athleticism and power to get to the rim any time he wants he'll have to settle for more jumpers late in his career like MJ and Kobe have. Unless he vastly improves that aspect of his game, that will diminish his scoring and shooting %'s greatly