Aircraft carriers can't use it. Supertankers can't use it. Those are, respectively, the two most "strategic" military and commercial vessels to the US (of course, none of the supertankers are our own anymore.)
Doesn't matter that much if the escorts of a CVBG can use the canal if the carrier itself can't. And there's no war scenario the US could conceivably face where getting lots of ships through the canal would be critical to victory. The US Navy's bases are split between each coast, and even half the US Navy is 10 times more powerful than any conceivable combination of enemies we could face in either ocean.
The US economy would not be crippled by closure of the canal, and neither would the US Navy. Not that it would be a good thing; it's just not the ultimate world strategic chokepoint as the conspiracy nuts would like to believe.