Dystopian pessimism is more sinister than that, I'm afraid. The spirit of pessimism is the idea that what ever you do, things go wrong, because we're bad. So there's no point trying to implement things. Whereas in optimistic fiction things go bad but the protaganist learns something and sets the world to rights by the end.
>>I only read stories to my kids that have good old-fashioned happy endings.
>That's actually kind of a modern development, itself.
Good point! Makes me think of Grimm's Fairy Tales, Aesop's Fables. Must take another look. (If I recall correctly these are moral tales rather than pessimism, however.)