Classical Music vs. Pop Music

Why do pop music/artists wear out quickly, while classical music/composers do not?

It doesn't matter what genre you're listening to, every artist and song sounds just like the other. Why does classical music remain strong and exciting, when pop music becomes weak and boring after a couple months? Just like the pop artists of today, classical composers "copy" other composers. For example: The trumpet solo in Hayden 100 (2nd movement) also occurs in Mahler 5. Hayden was dead and gone when Mahler was composing, so obviously Mahler is the copy-cat. It works though! Why can he get away with it? I guess the same is true in pop music: When Justin Beiber has a new hit that sounds like Usher’s new hit, it sells! But, the difference is Beiber’s “hit” gets old after a while; Mahler 5, on the other hand, is still exhilarating.  How come?

Composers develop a sound, or certain characteristic, if you will. Often times you can listen to a piece on the classical radio station and know with confidence that Beethoven is the composer. Why?  Because Beethoven has his own sound. You can hear his characteristic in each piece he composed.  The same goes with any other composer, or music artist. When the Black-Eyed-Peas come out with a new song, it sounds just like every other song on their album, and you know without a doubt that they are the artists.  After listening to it for a few weeks, though, it quickly gets old and boring. How come you can listen to Beethoven a thousand times and never get tired of him, but you can only listen to the Black-Eyed-Peas for a few weeks before you feel like pulling your hair out?  

The composers “take from” other composers, just like pop artists. The composer develops a sound, which causes all of his pieces to have a similar sound, just like pop music. What is different about classical music that makes it last longer than pop music?

I’m anxious to hear your thoughts and answers!