The great Lenny Bruce used to say that Tragedy+Time=Satire.
We can make dark humor jokes about Lincoln at the Ford Theater(for ex)
because there is no one left alive who knew Lincoln personally, or was
affected by his words and deeds in real time. No one who would be
personally offended, or consider such a "joke" cruel.
The Sixties Generation, and even folks younger, who were alive on that
terrible day in 1980, or when George left us, still have memories in
real time. It's not funny to us.