What the heck, I'll jump in on the Guns and Roses thing here....
I remember when I heard Appetite for Destruction the first time...I thought it was brilliant. Now, like Carnut I am much more metal than I am "rock," but over the years I've had my Aerosmith phases or whatever. In any case, I have always summed GNR up (for myself anyway) as having had one absolutely killer album - a classic. But, everything after that lacked the pizzazz of the first. To me, Use Your Illusion etc. and Appetite for Destruction sound like two very distinct and different bands. One I thought was good, the other I thought had nothing to distinguish it from any other hard rock band in the world. Sort of like the difference between Master of Puppets and Load. It would be like if Zeppelin made their first record, then went on to make a bunch of average stuff. So, perhaps the answer to the argument, in some small sense, is that Appetite for Destruction was influential, but GNR wasn't. Hard to seperate the band from the record I suppose, but hell, they managed to.......