My simple answer is it is not. I would think that an artist/songwriter would be happy that someone liked their song well enough to do a cover. I like to listen to covers of songs i like, to see how someone else puts their spin on it. Having said that, there are great , good and even garbage covers out there. And of course that is personal taste. Mona and Lisa do a fantastic job with their covers. That is how i found them. I was looking for covers of Beatle songs.
Keep up the good work Mona and Lisa and the whole team.