not that there's much use for them now, to be sure - but as a kid, this was one of those games I spent hours and hours and hours on trying to beat... I had always thought it was me not being able to figure it out (I had no way of knowing otherwise, really) and only now am I aware, because of articles like these, that it was practically unbeatable due to its shoddy planning. As for the quality, it was what it was, and it wasn't really any worse than the other games available for the 2600 at the time, so I didn't really know the difference. I liked it because it made me think about strategy in ways I hadn't otherwise yet learned at 8 years old, it taught me planning because I mapped out on paper some of the puzzle piece locations so I could try and find a pattern (sorta like D&D, even though I was never allowed to play that), and most of all because it certainly taught me patience beyond my years. I look back fondly at the E.T. game - not for the gameplay, but for what I learned as a young gamer because of what I now know are its flaws.
But yes, now that they're there in the ground, no real reason to dig them up - they're not going to be worth anything and all it really does is waste time and money to verify an "urban legend". Big whoop.