I disagree!
Oh man I'd forgotten that. Yes, I agree, this makes the existence of Nirvana worthwhile. The Territorial Pissings cover was ok, but I've honestly never heard the original so hey. The cover of Ministry's 'Thieves' on that album is pretty fucking bitching though. I shudder to think what the moshpit for that song must have looked like.
As for Nirvana not 'meaning' much to me because I wasn't around when they were making music, I don't think that applies. I don't personally rate any of what could be called 'my generations' seminal mainstream bands either. Nirvana had a few OK songs, which have been overplayed for the last decade. They ushered in a wave of music I consider almost universally shit compared to what had come before: I'd take even the shittiest eighties cock-rock over Silverchair any day of the year, and even the very best of grunge, in my opinion, is easily eclipsed by any Dio song you could care to mention. I don't dislike Nirvana because I wasn't around to feel their magic, in fact, if I had been, I'd have probably hated them a lot more.
Anyway, back to the thread. There are some bands that, whilst they should not never be covered, shouldn't be covered so much, but should be covered a lot less becuase they're so done, or should at least have less obvious songs covered. Prime examples are Black Sabbath and Iron Maiden. I must have about a hundred Iron Maiden covers on my computer, and about three that I consider interesting enough when compared to the originals to actually listen to (Sculptureds cover of 'Iron Maiden', Graveworms cover of 'Fear of the Dark', Therions cover of 'Children of the Damned'). Cover a Running Wild or Accept track or something, for fucks sake! With Sabbath the problem is more the lack of inspiration as to choice (though that's also a problem with Maiden). Everyons done fucking Children of the Grave and Hand of Doom. Why not try something a little more interesting or unusual for a change? I'm yet to hear a decent cover of Heaven and Hell, Wheels of Confusion/The Straightener or The Wizard.
Also, there are indeed more definite songs that should not be covered, or should at least be covered
very carefully. Bohemian Rhapsody and Comfortably Numb instantly leap to mind.