I was recollecting on something that Shawn Dickinson said in one of the commentaries we did together, and he mentioned the particular cartoon series (it was either Popeye or Bugs Bunny, I can't remember) being so fun to watch partly due to its constant portrayal of the suffering that the characters went through.
We humans go through pain and suffering daily! And with tons of different kinds of angst, it's automatically a form of therapy for ourselves to take a break and watch the characters on stage or screen get the shaft for a little while.
With that in mind, I think that audiences can identify with characters going through the same real human feelings that they do. Claude Cat and paranoia/hypochondria. Daffy trying to escape from fear.
Sylvester going mad from trying to deny his own obsession (eating Tweety).
Jealousy/hatred of others
Here, the Aristo-Cat is dealing with some people's greatest fear- being alone!
Death
Of course the Disney cartoons kept pretty far away from crazy stuff like emotional torment, but a lot of the Donald Duck cartoons are exceptions! Here he is on his deathbed in "Donald's Off Day".
Anyway, compare these to cartoons where everything is constantly alright and never in any real danger, and maybe you have films and shows that don't quite catch on as much.
What about cartoons where there is nothing human whatsoever?
Are cartoons not enough for you? Here are a select few of many TERRIFIC live action movies that revolve around manly, human suffering! See to it that they make YOUR favorite film list!
Detective Story
The Deer Hunter
M (starring Peter Lorre)
M (starring Peter Lorre)
Lots by Woody Allen, Wes Anderson and Hitchcock
and especially films directed by Ingmar Bergman: Persona, Wild Strawberries, or Cries and Whispers (one of the ULTIMATE movies about human pain!)