How dare we make art?

After World War 2, Karl Jaspers wrote a by now classic text about guilt, The Question of German Guilt. In his taxonomy, one of the categories of guilt is the "metaphysical guilt", which could be explained as the guilt for not sacrificing ourselves to help others. That is, living our lives and not doing everything we can to make a difference.
The question is, how far can we go? Shouldn't we abandon all forms of art (and entertainment), then, if we are to concentrate all efforts on saving the world? Is there an actual possibility that it would change something?
Of course, that sounds rather extreme. (And that's why Jaspers considers this a metaphysical guilt, shared by everyone and beyond the possibility of making it disappear in any way but through self-sacrifice). But somewhere here lie very difficult issues: why should one spend my time making quite self-centered installations when one could be working in an effective, world-changing organization? Should art be justifiable, like any other product, service, activity?
It isn't about art giving the possibility to do more. Because quite frankly the above video is an exception, and works exactly because it is one. Maybe, it is about the possibility of assuming uselessness?
Beauty is a great motivator. Indeed. (In João Fiadeiro's most recent performance (soon more about that), a sentence from Deleuze (roughly remembered by me): «I started reading Leibniz's Ethics. I am discovering that joy brings more power to act»)
But can we honestly say we make art, and see art, to motivate us? Isn't it a goal in itself? And if so, can't we spend our energy in a better way? How dare we make art?