think the reason is that I always think that National Anthems should be sung in the original version. (like what we learn in school...I'm just old fashioned I guess!)
Usually when these people sing them, they alter them, singing in a different beat/tempo, dragging the words out etc. I just prefer the original. Just not long ago when the Eastern Championships of hockey were televised, I heard someone singing the same anthem, and I commented then to my hubby that THAT was THE BEST I have ever heard it sung ANYWHERE, and it was sung by a man. It was in my opinion, PERFECT!