Performance aside, I've always considered them a creative expressive form of personal art. Heck, in most cases you have to design it on paper before you can make it. And I know a lot of fursuiters who display their fursuits like artwork. This is quite common at cons especially. Rarely do fursuiters hide their suits in a closet at a con, myself included. I have it out in my room to display for visiting friends. ;)

So to sum up. In my opinion, yes, it's art.