http://en.wikipedia.org/wiki/Music_Genome_Project
The Music Genome Project(link posted above) has changed how most people become exposed to new music. Less and less people listen to music on the radio, preferring instead to stream it. Pandora being one of the biggies for that, and at its core Pandora uses the Music Genome Project.
Even most people who do listen to top 40 dislike a good number of songs played but listen through them to hear what they like. With Pandora that's gone. Creating you own channels you never really get exposed to what you don't want. New stuff is mixed in but it is tailored to be what you already are predisposed to like.
Another change is in how the music itself is made. Heard an interview on the radio with Sir Mix a Lot. When he was asked about changes in the music industry over the course of his career he pointed to the massive increase of commercial grade music editing software available to anyone. Albums no longer need expensive studio time and can be made with a fraction of the upfront costs. He said that much smaller selling albums can now set an artist financially for life.
Think about the effect that has on the artists. Instead of trying to write the next "Thriller" They can focus on making what they are passionate for and still stand a chance to be financially wealthy.
BTW Spec, how can you throw up a list of music like that and not include the Black Keys? Edit maybe?... please.

of the internet, and technology in general (laptop computers which can be charged up with $500 worth of software that makes lil ol' me a better editor than any major publishing house from the '80s?!) when it comes to connecting artists with their audience.
And I'm all for people choosing precisely what they want in their entertainment media - I constantly harp about social agendas being far too prevalent in the stuff I consume for entertainment - but the downside to it is that there is very little chance for consolidated 'movements,' artistically, when everything goes meta as things are trending today.
The Beatles revolutionized pop music precisely because they had the bully pulpit. They had every microphone in a five hundred mile radius jammed into their faces whenever they showed themselves, and whenever they performed. The result of that is very similar to what world-wide communication has done for scientific advance: it creates a 'bedrock' or 'plateau' of substance and/or style from which everyone else can leap off. Generally speaking, in science at least, this is categorically a good thing since it consolidates knowledge and research to the degree that fewer lives are wasted copying each other's work in relatively fruitless directions of inquest. Now, some of the greatest discoveries have been made, essentially, by accident (the CMB, for example; you just had a couple of guys who were extremely diligent in creating a sensitive detection device, and it ended up detecting something even they could have never dreamed possible to detect).
With music, or any other entertainment media, this 'plateau' effect is understandably less important than it is for something like hard scientific inquest. But the effect, I think, can essentially be viewed as similar. Without the plateaus established by groups like the Beatles, the system begins to crumble into tiny islands which further crumble until there's not much value remaining, at which point it becomes a little more difficult to 'move forward/up' from the established position because that position was, itself, a decaying one (creatively speaking).
The great bands of yesteryear did indeed 'battle' each other artistically, and this competition drove them to explore avenues which had previously either been off-limits, or impossible (generally due to technological shortcomings of the prior period). The result was some of the finest music we'll likely ever hear.
I'm not arguing against the segregation of entertainment media, though. Far from it; I think the record labels and presentation medium (radio stations, popular culture, etc..) are genuine obstacles nowadays, as opposed to facilitators of great art. There was a time when I think they did, in fact, view their role (speaking of the media/presenters of music) as that of facilitators who were only too happy to take a slice off the greats on their way up the ladder. Nowadays, it seems the labels and popular media are more interested in creating solely-owned properties from thin air and then stamping them out before they get enough steam to head off on their own.
Bah, that's probably just incoherent rambling. Never mind...

Here's a couple links to Epic Rap Battles of History, an indie channel started by a couple of comedians that has rocketed to #1 status on Youtube. Several of their videos have over fifty million views, and one even has over a hundred million (Romney vs. Obama, I think). There are plenty more than these two that are great, but most of these guys' videos have language that isn't site-appropriate. This pair is clean, though...and the first one has Weird Al in it ;-)
https://www.youtube.com/watch?v=8yis7GzlXNM
https://www.youtube.com/watch?v=6HZ5V9rT96M

Has most of the bands listed above, plus a bunch that would never make it to MT. A song will come out there, and if its huge (car commerical background huge) then six months later clear channel will play it here. The Matt&Kim's, Panama Wedding's, Big Data's, and Junior Prom's will never make it to MT though, which is why I keep my XM membership current. So at least I know what the kiddies are listening to, even if it is more sythesized than I prefer. There's not alot of new, good music, but there's some. Any contribution to the new AND good music should be appaulded considering all the 3 chord songs have been done before....cool thread.