Why is Nirvana still played so much on the radio?

Can someone please answer me this? The band has been dead since 1994. It has sold 50 to 74 millions records, according to wikipedia. This puts it WAY behind other popular, contemporary rock bands that have sold much more music than they have, such as metallica, depeche mode, and guns 'n roses, to name just a very few. But do you hear these bands on rock stations as much as Nirvana? No, you don't. At least, not around here. Why can't we just let them die? They really weren't that talented of a band. Is the ghost of Kurt Cobain haunting the owners of large radio stations, forcing them to play his music incessantly? Are they still played to remind us of the roots of the currently-popular Foo Fighters? I don't know. KROQ (local rock station) ranked them as the #2 band of all time (at least, in terms of what they play apparently) as of Memorial Day 2007. #3 was Sublime, which, incidentally, was my next question. Why is SUBLIME still played so much?? Please. Let these mediocre bands of the past rest in peace. The fans who really care will still buy their cds and keep listening. But if you describe yourself as a rock station that plays "new" music, don't insult my intelligence and play old early 90's hits over and over like they just came out last week. Save it for "90's at noon" or maybe themed weekends where you play old hits. There are so many good bands (note, this does not in any way include the no-talents "Social Distortion") coming out with great music nowadays that you should have more than enough to choose from without resorting to bygones.