In 1941 we didn’t have a torpedo that could work in shallow water like Pearl Harbor.
And despite the fact that the Brits apparently did have one, we decided that Japan didn’t. Which of course they did, the ‘Thunder Fish’.
Combined with a belief that Japan couldn’t possibly send a fleet 4,000 miles across the Pacific without us noticing, we thought that the fleet at rest inside Pearl Harbor was safe. Japan proved us wrong on that conceit as well.
Other than the loss of life Japan probably didn’t hurt us all that much. The warships at Pearl were old and slow compared to the Fast Carrier Task Force that we needed and built and used to defeat Japan.
The Japanese probably did us a favor at Pearl Harbor. They sank some obsolete battleships, but the crews mostly survived. They destroyed some obsolete planes on the ground, but most of the pilots survived to be given new planes.
The strategically important ships, our carriers, we’re not there.