Is it ALWAYS necessary to understand words of song?

...throughout my devotion to music of different kinds and songs, I've realized that songs of Paul McCartney, Queen, Led Zeppelin and other Brittish rock bands motivated me to learn English.
I am learning French now -- guess for what reason?
-- Very simple:
I adore french femail chansons such as Mireille Mathieu, Edit Piaf, Juliette Greco, Patricia Kaas.
I also like male singers Joe Dassin and Charle Aznavur.

The fact is that on the first place I did not understand neither English or French.

There are other performers that sing other than in English or French that I like and do not understand what they're singing such as Gipsy Kings(Spain), Cesaria Evora(Sinegal), Los Joven'os Flamencos(Spain), Nina Hagen(Germany) etc... but these performers did not yet motivated me to learn their language since they're almost "one of a kind"

It is almost impossible to aquire non-english/non-latin CDs or records on the territory of US. The're all either in Canada, Europe or even Asia!

For live performances,for example, Nina Hagen(Germany) didn't sing any of her songs in German in NY. It's very rare or almost never in US that popular rock/pop singers from european countries other than UK will perform since they probably have to sing in English.
The only exception I know is Cesaria Evora that sings in Portugese. She performed in Carnegie Hall and Beacon Theatre in NY.

I was on live performance of Mireille Mathieu in Kiev, Ukraine where I can bet that most of the ticket holders did not understand French. In fact, there is no need on the first place since her voice and artistic scene play makes people understand her without knowing her language. She crossed over the whole World with her live concerts except US.

Please share any thoughs and/or arguments. Is there anyone who listens songs without understanding words?
If yes, tell who do you like, what language he/she sings and what country she's from?

Hopefuly in few months I'll make a post in French!!
HeHe!!!!