We owe it to the music we love.
We owe it to the music we love because memorized music is better learned music. By memorizing music, we are not obstructed by physical objects such as pages and lighting. We have a more solid technique through the process of memorizing. We have a better conception of a composer's sense of form, phrase, and harmony. We are more disciplined in our own practice because of the demands of memorization.
We owe it to the music we love because memorized music is more engaging for the audience. We choose only the best repertoire to commit to memory. We appear before an audience only when we feel that the music is ready to play. We create convincing and well-conceived interpretations through the process of memorization.
I could go on and on with this litany!
Even if you don't believe in the second paragraph above (that memorized music is better learned music, etc.), it's hard to argue that playing from score is more engaging for the audience. It's just as hard to argue that there's no difference for an audience.
And this comes to my final point. Is classical music dying? Maybe it is, maybe it isn't. But one can hardly argue that classical music is very healthy or that audiences are just dying to hear the next recital.
As I already wrote:
Think about it, classical musicians. We don't have audiences screaming for our music, and we've been fighting a tide of pop culture for a very long time. We need to do everything we can to bring in and retain our audiences. While memorization is only a piece of the puzzle, I can't imagine that audiences--especially new audiences--want to watch us read music when they've taken the time and money to sit down and quietly listen to us. We owe it to our audiences and this repertoire that we love to give our best, and this includes working ten times harder to play this music convincingly without a score.It's time to do something about this. And now it's time for how.