It's really hard to figure out why Hollywood will make one historical event into a movie, and not another. Probably a myriad of factors involved, but I'd think that $$$ drives the whole decision making process.
When an inexpensive movie makes a load at the box office, Hollywood behavior is reinforced to make another of the same kind. Hence, the current status quo of sequelitis.
I assume making historical epic movies cost much more, due to shooting at exotic locations, etc.
It was rumored that we get a movie entitled "Tripoli," but I think it got canceled.
Tripoli (2009)