1. I'll stipulate most of rock on radio has sucked for 10-15 years. White stripes, strokes, killers, and all the stuff you named. Some of it (pop and pop rock) is the same studio over-production, just auto-tune instead of computerized beats, while the other side of rock went super indie, low-fi, and sound godawful, but its the same end result: mass produced, not-good music, on the airwaves and winning awards.
2. Classical has stood the test of time for hundreds of years. So has opera. You think anyone will remember Puff Daddy in 2090? Spouting bullshit about its place in musical canon just goes to the heart of your inexperience and lack of knowledge. Not saying it's the end-all be-all, but if you can't even appreciate it, you probably shouldn't be talking music.
3. I've worked in-studio with up and coming rappers. I've had to try to give them basic musical lessons (the horror). I've heard the raw first takes, and engineers working on it for weeks afterwards, adding sounds and other artists to 'feature' while the *talent* gets tatted up and works on a six-pack, or maybe gets into legal trouble just to get cred. I've seen them take an 18-year old virgin girl and make her rap about the ghetto and all the sex she had, so that they can push a persona and release a product, the next Iggy Azalea or what have you.
So what percentage is manufactured WWE, McDonalds crap? 50%? 80%? I don't know for certain, but I'd bet 90%. Again, if you find someone credible as an artist, and really buy into what they are doing, good for you. Realizing the truth behind what's going on doesn't stop you from appreciating whatever % is decent, non-frankensteined material.
I think it's easy when you're a teen to think that everyone else is on the outside, their opinions are fallacies, they don't "get it". The truth, however, is not so simple. It's usually just a truth you don't want to hear
