I agree with everything you said, but think the reason we put into a classification instead of just "good, bad and weird" is because my idea of good may be no where near yours. Generally speaking, there are few of us that actually like all types of music, some say they do but I would wager that most do not. I consider myself really open minded and listen to a great deal of music spanning many genres, but I can't listen to Rap. I just cannot relate to it on any level whether that be the instrumentation or cultural significance. So therefore, it you said come see this concert with me the music is great and I got there and had to endure 2 hours of rap........Well, let's just say I could have avoided it right from the get go with a little musical classification up front.
I'm not going to tell you to go find some "good" hip-hop but I will tell you it's there. Complete with lyrical depth and musicality. But I've been right where you are with country radio in the 90's, said I hated the genre and you couldn't drag me to a show. Took some time to get there via some alt-country bands but I'm so happy I found the real stuff. Same with hip-hop, same with bluegrass, same with jazz, same with funk. I agree it's all based on taste, which is why genres are even more ridiculous because there is no way to tell if it's good, bad, or weird based on a designation.
Let's start classifying bands on a scale of 1 - 10, 1 being the poppiest radio hits written just to sell records, and 10 being the most self-absorbed with no regard to an audience. Then we can all say "I like bands that are a (insert number here)" and we all know what records to buy you for christmas.