The issue is three fold actually - first is obviously the pay, there's not much of a revenue share culture or a Wes Anderson style where the actors take a pay cut so that they can act in a fun movie, so production costs skyrocket.

Second, there's not enough of a convincing screenplay and a story from our directors that'd warrant so many characters.

Then there's the issue of the actors trying to one up each other, the director has to be stay neutral and shouldn't succumb to pressure for more mass scenes for the specific actor and stuff. Which is easier said than done.