It's actually the only long term approach -- literally. It's not ignoring reality, rather, it's choosing not to lose hope that we can create a better future.
Because, as we've seen, the world is what we make it, for better, and for worse.
If we look at WW2, you see Neville Chamberlain, the optimist, pursuing a policy of appeasement giving Hitler the benefit of the doubt and proclaiming "peace for our time" after signing of the Munich agreement. Meanwhile, Churchill, a realist, realizes that Hitler is not going to stop until he's dominated all of Europe.
So who do you prefer to be in this story, the naive optimist Chamberlain, assuming everything will be okay? Or the realist Churchill who recognizes the threat, and takes the necessary evasive action.
Churchill was a combination of a realist and an optimist / idealist.
To paraphrase, "reality is that which, when you pretend otherwise, continues to be the way it is."
It's a nice thought, but proves to be difficult to implement long term. Sure you might convince yourself for a few months that things are like X, ignoring the evidence that they are Y. That's your prerogative, you can operate in whatever reality you wish. Eventually reality catches up to you and you have to pay the piper.