The Japanese attacked the US pacific fleet at pearl harbour.. but why did they not attack the actual island also with ground troops? were there many infantry units based there? Would controlling the island not have been better as it would have denied the US an important base and been an ideal point from which to defend attacks by the US deeper in the atlantic?
John Parshall, one of the authors of Shattered Sword (one of the major texts on the Battle of Midway), published an article on his website . The long and the short of it is that Japan simply did not have the shipping resources to take the islands, despite the strategic benefit they would have accrued. The American garrison was much too large for the Japanese amphibious forces to actually take the islands.
Rough calculations show an occupation force would require between 45-60 cargo ships to sustain the islands.
Also, being further out would make the islands themselves more vulnerable to attack. Depending on how that went, it would have at best bought them a little more time, and at worst consumed enough resources to hasten the collapse.