Nobody wants to hear anything new. Adoption comes from fashion, appreciation is rooted in familiarity and nostalgia.
When I go out to meet friends, everybody's dancing to the same old songs they have been dancing to since they were at school. Sure the Happy Mondays were great but do we really have to listen to
Step On every night until the year 3000?
Meanwhile the kids are being fed regurgitated versions of songs from thirty years ago - once, twice, three times digested - minor mutations - a bit of spit and polish - I can't blame them for loving it - they don't know the originals. I was the same.
I was excited by a night out at a club full of young twenty-somethings - the music had satisfying modern twists (all I ask is for a bit of wub-wub bass here and there! my tastes really aren't so complex!) But I find it unutterably depressing that the most edgy music I can expect to ever hear in the company of others (i.e. pretty girls) is a handful of ageing grime classics - the I Luv U, Shake A Leg and an Eski beat or two.
As fashions tail off, a handful of representative songs gets sealed off into bags and labelled up: '60s Music', 'Electro', 'Drum & Bass', 'Indie Rock'. DJs queue up to select one of these bags and we go and listen to them playing their tired contents. We may then select one of these labels and go out to hear this predictable selection of songs and get wasted, comfortable in the knowledge that we will not be expected to process anything we haven't heard before.
Pop music needs nourishment - there's a limit to how far it can re-digest itself. It needs fresh blood. All this inbreeding is a perilous practice.Wall-E cheerfully presents the future we are heading towards. Utterly devoid of art. Nobody taking risks, or even understanding the concept of risk. A populace blindly adopting identical fashions. Yet oddly content. Personally, it is not a world I want any part in.

DJs know what will please a crowd. I don't blame the DJ for being cagey about trying out new tracks - I blame the crowd for being closed off to anything new. There is a universe of interesting, exciting, beautiful and uplifting music out there that we could all by enjoying. If I am expected to make an effort to dance to something I'm tired of, why can't everybody else be expected to try to dance to something they haven't heard before? Imagine how much richer everybody's lives would be if they opened up to music as an art-form instead of viewing it as wallpaper, dancing only according to their level of intoxication?
(I suspect my problem lies with British culture, where nights out, and music writing, are usually more about the drugs than the music. Tedious.)
When people on dance-floors hear something that makes them uncomfortable, I wish they would put in some effort to engage with the music instead of giving the DJ a hard time. New things are inherently uncomfortable; prejudice toward 'outsiders' is a base instinct that needs to be trained, it's a negative force of human nature. If people conquer this instinct, their lives will be immeasurably richer. Art would be an easy place to start.