A German friend of mine sang me a song in Dutch last night. Sure, it
wasn't like a native would sing it, but I liked it anyway!
I try to sing songs in other languages too, even if I'm not fluent, I thinks it's a lot of fun. What's the harm in that?
I think it's different if you pretend to be a fluent speaker and you really aren't...
Anyway, many successful pop/rock singers who sing in English aren't native speakers either.

Letty