They were a cute gimmick back in the days of LPs, but they're just plain irritating when I'm doing most of my listening on a shuffled iPod. It's especially annoying when it's a really good last track, ending with several minutes of silence, and then a cutesy final song that isn't nearly as good: this often makes ripping the track more trouble than it's worth, since I don't want that silence to show up in Shuffle Play. (Yes, I can snip it at the start of the silence, but it's a hassle I'm tired of.)
Really: enough is enough. It was clever the first thousand times, but it's an idea whose time has long since passed...