Why does Mexican music sound the same now as it did 20 years ago?

I happen to enjoy the Hebrew favorite* Hava Nagila*, yet for some reason Jews are not inclined to be blasting the song out of their Cadillacs! There is a lesson here for Mexicans.

http://www.youtube.com/watch?v=BFtv5qe5o3c

Found this looking up the above link.

The only group of people I know of who are not afraid to make fun of themselves for the world to see are the Hebrews. Who beside the Jews would do this to one of their legendary songs, Hava Nagila? This song is about 50 years old, but you will see their well-known sense of humor in it.

http://www.youtube.com/watch?v=roAWodrsZXI

Twenty years ago was 1991. What has Anglo music done in that time? What, a little more techno?