One answer to this question lies in President Roosevelt's ["day of infamy"][1] speech.

>"Yesterday the Japanese Government also launched an attack against Malaya.<br>
Last night, Japanese forces attacked Hong Kong.<br>
Last night, Japanese forces attacked Guam.<br>
Last night, Japanese forces attacked the Philippine Islands.<br>
Last night, Japanese forces attacked Wake Island.<br>
And this morning, the Japanese attacked Midway Island."

The Japanese were engaged all over the Pacific, and spread very thin. Pearl Harbor was the farthest away of their targets, and therefore the lowest priority for occupation. The Japanese might have attempted Hawaii *after* capturing all the other targets above, to extend their base, but not before. Their goal in December 1941 was to neutralize Pearl Harbor, specifically its fleet, not to occupy it.

Regarding "paratroopers," Hawaii was a lot farther from the Japanese bases than Crete was from say, Greece. The "paradrop" on Crete *barely* succeeded, suggesting that a similar attempt on Hawaii, without the ability to reinforce and resupply the invaders, would have failed.

[1]:http://www.awon.org/dc3/