Having just reorganized our central living space, my sons room and part of the basement, I find that organization brings peace, a fresh perspective and added focus. The peace comes from orderliness, everything having a place and complementing the overall scheme. A fresh perspective occurs because when I 're'organize, I invariably re-order: moving things about into new configurations, eliminating clutter and throwing away trash. The space(s) feel new and newly interesting. The added focus comes from knowing exactly where everything is and where everything belongs, so I can avoid lost time.
PS my MP3s are organized only by artist, and I do that when I up/download them. To organize them beyond that would just be pointless busy work for me.