I got the idea for this from the 'looking serious' thread. U2 did the Super Bowl in 2002. Would they have been asked to do it sooner? No. They were not asked to. Why? Was it because they as a band had reached a place where they were popular enough, well known enough, and accepted by enough people? Was it because rock and roll was?
Okay let's discuss this. I remember back in the 80's the halftime shows were usually cheesy shit like 'Up Up With People!' They had to be something generically accepted by a wide variety of Americans. (yes the Super Bowl is shown world wide too) In the early days of the Super Bowl, hell would have frozen over before a rock and roll band would have been asked to do the halftime show. Can't you see a million rednecks throwing beer cans at the TV when The Doors came on the field? But, as the years went past, rock went from being rebellious, counterculture, and bad to most grownups to something that was acceptable and even enjoyed.
A big reason for this? Time. The 'kids' who had shocked their parents with rock and roll had become parents, some even grandparents! So, these people, rock fans, went from being the rebels to the target audience for advertisers! Now you even have Led Zeppelin doing car commercials! That would have been unheard of in the past, even 10 years ago. But times have changed, the demographics changed, and so did the acceptability of rock and roll.
Okay let's discuss this. I remember back in the 80's the halftime shows were usually cheesy shit like 'Up Up With People!' They had to be something generically accepted by a wide variety of Americans. (yes the Super Bowl is shown world wide too) In the early days of the Super Bowl, hell would have frozen over before a rock and roll band would have been asked to do the halftime show. Can't you see a million rednecks throwing beer cans at the TV when The Doors came on the field? But, as the years went past, rock went from being rebellious, counterculture, and bad to most grownups to something that was acceptable and even enjoyed.
A big reason for this? Time. The 'kids' who had shocked their parents with rock and roll had become parents, some even grandparents! So, these people, rock fans, went from being the rebels to the target audience for advertisers! Now you even have Led Zeppelin doing car commercials! That would have been unheard of in the past, even 10 years ago. But times have changed, the demographics changed, and so did the acceptability of rock and roll.
good point. i think the first commercial i remember seeing that had music (like a rock and roll song you could actually identify, not just random crap music) was for nike, using the beatles' "revolution." if that indeed is the earliest case or one of the earliest (i don't remember a lot of old commercials due to my age), then mayhaps michael jackson can be given credit to commercializing rock music like that.
Now my next point: when did rock stars "selling out" become acceptable? I mean, acceptable to the mainstream marketing people, and acceptable to the artists? I remember the backlash and uproar from the entertainment world when Phil Collins sold his song to a beer commercial. What a terrible thing! Or, was it?! Maybe it got people thinking, hey, it's money, it's exposure for us, but ultimately, it was exposure and acceptability for rock and roll and the rock culture! Yes, aging baby boomers were a big part of this becoming so, but the artists had to do their part. When Robert Plant did the "Tall Cool One" Coke commericial in 1988, I think that opened the flood gates that took this from being scorned to commonplace, almost cool. Now you have legendary bands like The Who, Stones and Led Zeppelin doing big name commercials. (The Beatle songs were sold out by Michael Jackson, who owns the rights.) Even punk boy Iggy Pop has sold "Lust for Life" for money! U2 refused a 23 million dollar offer to sell "Where the Streets Have No Name" to a car commericial because they felt it was too special to them and their fans to remind people of a commercial. Good for them. But you can't blame those who do sell out, even if they don't need the money. I admit I cringe every time I hear The Who in that sinus medicine commercial, but I do feel almost happy in a way that they were wanted, that "they," the big man in the office on Madison Avenue, who used to condemn rock and rock stars, wanted it, got it, and used it. A lot of counterculture people must feel a gloat coming on inside even if they don't admit it, and Jimi Hendrix and Jim Morrison must be rolling over in their graves at the shock. Or are they laughing somewhere? 
it's not really fair. me, i tend to only not like the ones who tend to overdo it, who license seemingly everything. i would say the rolling stones has sold out, as has michael jackson for licensing so many beatles songs. but someone like sheryl crow who's only licensed one song (that i know of!) isn't bad.
My friends and I have spent alot of time wondering the same thing. One's prediction: music will lose all semblence of melody and people will just be banging, loudly, on things.
So much for hippy, anti- 'the man' values. Or, again, how wonderful that they were wanted! Perhaps, the ultimate victory, but in a way they least expected?! 
