I love having pretty jackets that I can wear when it's cold, but for some reason my jackets are always losing their buttons. I have suspicions that this is due to 1) Factory-sewn buttons not being very durable and 2) Me buttoning my jackets all the time because I am so dang cold. I replace the buttons on these two jackets, and instead of just saving the old buttons to sew back on (mostly because I lost them) I found new ones. The brown jacket's new buttons have pretty pearly shells in the middle, and I thought red was a much more suitable color than blue buttons for the longer jacket.
And I think this is also useful if there's jackets you have that you don't like the buttons, or if you're bored with the piece. New buttons sure can change the look of a jacket!