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I really don't know much about popular music, but I'm guessing that music from video games is getting more popular now, because when I ask people what they are humming they usually say it's a song from a game. But maybe those songs are just more humm-able, and the songs that I hear people humming are not a representative sample of all the songs that they listen to.
About updating the language, if you mean the abbreviations and phrases that people use in texts, I think that people do it so that they don't sound overly formal. Sometimes writing a complete sentence in a text would be like speaking to a friend in rhyming verses.
I think the kids I know get most of their information (and opinions) from their parents, and a few things from other places to make them feel grown up (I do this too). I think that because I often hear a friend saying something and then I find out later that that is what their parents think.
(sorry it took me so long to respond)