[NoPiece]

I think it is the opposite. Star Trek was hopeful in a time when a real threat of nuclear war loomed, Vietnam was showing the horror of war on TV every night, there was civil unrest (both anti war and civil rights), JFK has recently been assassinated, and RFK was about to be assassinated. It was a hopeful alternative to the present of that time.

[protomyth]

If we are talking TOS, then "A Private Little War" isn't very optimistic at all.