Which is unfortunate because bigots often take strength from projecting an air of dignity and respectability in an attempt to legitimize themselves in the public square. It's why modern white supremacy and anti-semitism have been reframed as science and philosophy, merely a skeptical form of racial and political realism questioning the mainstream narratives of progressivism and the Enlightment.
Using humor to debase those ideologies and humiliate those who hold them could be a powerful weapon, robbing them of their potency.
Of course, not all such humor has noble intent. The difference between Mel Brooks using racial and religious stereotypes for comic effect and, say, /pol/ doing the same is who the target is, and whether the joke is "punching up" or "punching down." Punching up is funny, punching down isn't. For all of the crass and racial jokes he would make, he, as a white man, still refused to make a joke out of lynching.
That's not at all true; except perhaps for extremely historically-grounded drama (which Django is not), drama tends to get less license than comedy.
> but Mel Brooks' style of humor is no longer socially acceptable
Mel Brooks style of humor was never “socially acceptable”, it’s was always transgressive. It's probably not as commercially acceptable in the mainstream film industry as it once was, but that's more because transgressive video entertainment has other outlets and the mainstream film industry is a more mature and more narrowly-focussed industry than it once was.
> We can take issues like race and anti-semitism deadly seriously, but we aren't allowed to laugh about them anymore.
My experience of currently successful (both live and distributed on major video platforms) stand up and other comedy suggests that, yes, we are very much still allowed to laugh at those things. The particular currently successful forms may not look exactly like Blazing Saddles, but while the latter isn't stale, it's also very firmly grounded in the time it was produced (which seems generally true of Brooks’ comedies).