We look ahead at 3991 AD and find it to be depressing. I've always wondered how past civilizations (Greeks, Egyptians, etc) would find our modern day civilization.
And looking forward, I wonder what future civilizations think about their future. What kind of science fiction do people on Star Trek read? It's a convenient cop-out that everyone on the Enterprise is a fan of mid-20th century pop culture or Shakespeare.
Its because we have had peace for so long, we fear we might loose it, so the dominant emotion is not hope of getting better, though that exists, but fear of getting worse.
Past civilizations mainly were in war with each other, so their dominant emotion was probably hope that things will get better, thus they dreamed.