Well, that isn't always the case.
I have a bit of a facination with Jim Henson, it is a long story that I won't bore you with but when the stamps celebrating him came out a few years ago I bought a bunch. Not to be used, no... too special for that. I put 2 sheets together and framed them.
I've got this hanging in my office, it is home with me for a few days, something about it has given me an idea for a new project.
We'll see if it turns out...