Pop music used to be music that simply appealed to the broad masses. But, the music output changed as the state of the US economy did. As we shift more and more towards companies manufacturing wants, instead of manufacturing solutions to those wants, we find that the music industry's "pop" music becomes increasingly more trend-setting and not trend-following.
By that, I mean that people like Hendrix, inarguably a "pop" star, reflected the ideologies, desires, and wants of a huge demographic of people. Now, however, "pop" music is so formulaic that it seems to be crafted as generically as possible, with certain algorithms and formulas set in place to make sure that there's no deviation from the norm, while the actual "pop stars" focus on selling products and pushing brand names to make their money and get their name out to the general public.
There is nothing wrong with this - I have huge respect for anybody trying to make it in this aspect of the music industry. However, it is inaccurate, from my personal experience (and the written consent of others), to suggest that pop music hasn't seen a miraculous shift-of-curve, so to speak. The music industry, thanks to the shifting economy and the cheap freedoms new technology provides, has become a lot more polarized, with most music either being very 'manufactured' (Fallout Boy, ***** Cat Dolls, 50 Cent, Green Day), or very unique (countless no-name groups under the support of indie labels).
The manufactured "bubble gum pop" records used to not out-sell the other more sophisticated and unique "pop" records such as that by The Beatles, Hendrix, Zeppelin, et cetera. There was more gray area. Now, although, there is certainly more black and white. This can be perceived as a good thing, as now more people are becoming more adventurous in their tastes and diving into the unknown worlds of experimental, jazz, classical, and really "old" stuff like country blues (Leadbelly and Johnny Cash have seen revivals recently).
EDIT:
I just noticed the argument earlier in this thread about songwriting credits towards these bands. The majority of major-label groups like Fallout Boy do write at least some of their lyrics. Although, they are heavily revised by uncredited lyricists - professional "vocals producers", we'll call them. They are very high paying jobs - there are a few per major label - and their objective is to simply "perfect" the lyrics while still maintaining the rhythmical and logical structures to the words (and also maintain the original artistic purpose). The credits go to the band because part of their high payment is due to the fact that they must sign away all of their artistic contributions. This is not unheard of, and has been going on for a couple of decades now in the music industry. You see it happening more and more with "alternative" groups like Fallout Boy and Greenday, since it has become socially unacceptable by the general public to simply 'interpret' somebody else's songs. Boy bands and the Britney Spears types used to do this all the time in the early 2000s and the 1990s, but, rightfully, even most tone-deaf teenagers have found it improper for this practice to occur. So, instead, the professional lyricists are contracted, intentionally uncredited people who commercialize and "plastic-coat" the lyrics.
