How do you rationalize audio upgrades?

To my way of thinking, an upgrade has to do one of two things in order to be rationalized/justified....add an improvement compared to what you already have or eliminate a negative that is just eating away at you.  99% of the time, these will be sonic/musical in nature...but every now and then, aesthetics may come into play.

Oh...and one final thing...whatever change is being contemplated should not result in seriously reducing other important aspects of your life.

I think it is also fair to say that in many cases, tastes, wants and desires change over time...and if/when this happens, your current audio system may no longer provide the enjoyment that you expect which then requires some "tweaking".