I, like many other people in the topic, own sealed games that are sealed because I haven't gotten around to play them. I've slowed down on this habit, however, so I only have one sealed game. Of course I've never found any classic sealed games.
I did have some second thoughts on opening a game. A few months ago I was planning on playing Viewtiful Joe. I had purchased a copy at Target when they had a deal on Player's choice games, but never got around to playing it. I thought to myself that it might be worth something someday if it reaches cult classic status. I did decide to open it though as I really wanted to play it.