In order to fail at not coming off as an elitist jerk, I will not use the term "good" in this thread since each listener determines what music is good on their own. I will say, however, that there is plenty of well written, expertly played music available today by modern bands and artists. You just rarely hear it on the radio (this is the part where I fail). Most radio friendly music is designed to be sold, consumed, and then discarded when the next "big thing" comes around. In that capacity, it mostly works.
But then again, this is nothing new. The majority of people who tell you that the music was better in their day are talking about the same shrink wrapped, by-the-numbers bullshit that is prevalent today, just from a different era. Don't listen to them. There is nothing inherently superior about their consumerist crap than yours. And I mean that. I don't listen to most radio friendly music (because I have a passion for music) but I do watch bullshit throwaway movies. I'm a consumer at heart too.
As for the blandness of rock and metal, well you've got two things contributing to that:
1) Like I said, shrink wrapped, by-the-numbers bullshit. There's diverse, well-written music out there, but you aren't going to hear it unless you search for it because it sure as hell isn't being broadcasted on the airwaves (well maybe on XM/Sirius). Instead, you get music aimed at a demographic, which means that the studios find a band that can sell and then imitate, imitate, imitate! Is it any wonder that most rock/metal sounds the same?
2) The Loudness War. Since the 90s there has been a trend among the studios of mixing music louder as a way of standing out and grabbing your attention when it plays on the radio. Unfortunately this is a horrible thing to do, as you have a limit on how loud music can be mixed, as there is a "ceiling" of sorts that the waveform will eventually bump against. When it does that you get something known as "clipping." Add to this that the studios started mixing even the soft parts of a song louder and you get the audio equivalent of squeezing play-dough through a tube. There are no highs or lows, just a long, boring wall of sound. Goodbye dynamic music.
Regrettably, there are very few bands today that do anything about the second problem (Thank you Porcupine Tree), but the first is easy enough. Don't look for bands to listen to solely by listening to the radio. Yes, you can listen to radio friendly music; I've already said that there's nothing wrong with being a consumer (if there is, then I am equally wrong). Just look for something more as well. I watch throw away action movies, but I also enjoy movies like A Beautiful Mind, Let the Right One In, and anything by Akira Kurosawa.
I'm Scars Unseen, and I am an (occasional) elitist jerk.