This is such an interesting question, and I have so many thoughts on it that I don’t think I can express them all here. Note that the following are merely my own musings, and they may not make sense or may even seem silly. But the nature of this thread and the deepness of the thoughts on this matter call me to respond.
I agree mostly with everything that m1469 has said. I can even identify with a lot of it. I think that I should play music for the sake of the music, or for God. I believe that music is really something divine and sometimes I wonder whether we can really give it its due and really perform it without inspiration from above. When I think of that, I wonder how much the musician really matters.
Some have said that they use music to express themselves. But that doesn’t matter enough for me. Sure, I have done it, especially when practicing privately, but I doubt the audience cares how I feel. But more so, perhaps the music should be performed to express the glory of the universe and of creation. In such a case, perhaps it could be said the musician is merely a tool to this end. The musician must practice so that, going by this analogy, the tool functions properly, but the inspiration and the interpretation cannot be practiced.
This makes me feel guilty though. I admit that I want to be a great pianist, as I know many people do. To what else do we aspire if not to be great? But in this view, it is too much about us and not enough about that which I just mentioned. Maybe that’s why some of the greatest pianists of our time are sometimes said to be virtuosic technically, but poor in interpretation.
But I don’t know to what we aspire if it is not to be great. Or maybe it is to express the music in the purest way possible, without the constraints of our technical ability.
But mostly I see this as only applying to classical music, and perhaps not to what others have mentioned as regards playing for parties and so forth. But then, I see classical music as the purest and highest of the musical forms, with no offense to those who prefer other forms.
Therefore, to attempt to summarize, I find a conflict between what I feel should be, and what often is the case for myself. It saddens me and strikes me with guilt, but I don’t yet know how to resolve the two.
What really does matter in the long-run, after all, is not ourselves but our expression of that music. The music is above time, but we are not.