Finally the Cities of Los Angeles and Santa Monica decided to put a stop to this very unhealthy but entertaining situation and made fireworks of any type illegal on the beach. They encouraged people to attend fireworks shows in their own neighborhoods and told everyone that if they were found with fireworks on their person that they would go to jail.
Some of us, more conspiracy minded, wondered if they woke up to the realization that they had created the potential for a serious civil disturbance. Lets say on a very hot Fourth of July some Latino got hassled by the incredibly racist and violent LAPD and did not fall to his knees in abject submission as all minority groups are supposed to do. The LAPD would naturally beat the miscreant into bloody unconsciousness which is their standard procedure in such circumstances (see, for example, Rodney King). And suddenly you might have a riot on your hands with the minority groups already in the wealthy parts of the city and armed with M80s and other minor explosives.
But probably those who mismanage LA are actually not smart enough to come up with a reason like that, and simply wanted to lower their costs and minimize the injuries to try and prevent the otherwise inevitable lawsuit.