As for the second part, I'll give you credit there, not much has changed, but knowing WWE they wouldn't want to risk the slightest thing. They've been too corporate lately.I just doubt most of the fans would really notice.
As for copyright law, the laws themselves haven't changed. The way they're applied has, thanks mainly to the increase in the sampling of published/produced music in hip-hop. If they change enough (and what is "enough" is an open concept and argued widely in copyright courts and law school classes everywhere), the originators of the song have no grounds upon which to sue under copyright violation. That was the genius of JH when he used to do them all the time (it didn't hurt that a lot of the territories were regional at the time and a piece of music he adapted in Georgia or Tennessee might never be heard by the originators of the song who were living in L.A. or New York).
wk
As for the fans, I think they would notice considering how on most social media they blew up over Rose's theme change.