I'm not sure why, but I sure am glad that Metallica did. Because now, every time some smartass yells up at the stage at me (JUST me and my guitar mind you!!), Metallica!!!! I jump right into a rousing version of Whiskey in the jar! I had a rather inebriated "gentleman" who frequented a bar where I played on a regular basis swear that I was wrong and he proceeded to bet me $50 that Metallica never recorded the song. I carried a copy of the song with me for several gigs back at that bar....he, however has not returned.......imagine that.
Btw, I also love it when someone wants me to play Pearl Jam! I have played a J. Frank Wilson and the Cavaliers song for years and Pearl Jam was nice enough to butche...uh....murde....uh, well, COVER the song. In any case, they ask for Pearl Jam, I play "Last Kiss". I offer them a drink if they can tell me the original artist....I've never lost.... :)