Their music. They perform it. Just because they didn't write the music doesn't mean that they can't say it's their music. Using that logic, the majority of pop stars are just about lose the right to call their music theirs. All those classical musicians that are performing the works of others are suddenly nullified and what they have brought to the performance is void?
If it's not for you, you could have just moved on.
Did you have some salt on your Frosties this morning?
I enjoy some of their takes on songs, not always. But I don't need to justify what I think to anybody. Just enjoy music for what it is. If it talks to you, enjoy it. If it doesn't, move onto something that does.