Tribute bands simply fill a slot. People want to be entertained and hearing songs by a famous group is a far second best from the real thing but it can be fun. Original takes on songs is great "if" you have and audience that appreciates it.
Sort of on topic I'm reading the biography, "Good Lovin", of Gene Cornish , guitar player in one of my all time favorite groups the Rascals Very interesting to read some the the truths after all the years of rumors and misinformations about them.
I've often wondered why I've never seen a Tribute Act based on them. I've see Felix's different incarnations of the Rascals 3 times ( lent him my B3 for one ) and was lucky enough to see the reunion show "Once Upon a Dream" before it folded. They were such a kick a** live act I think it would be great.
Also if you like tribute acts with a bit if a twist look up "Tim Ackers and the Smoking Section" His band does some unbelievable arrangements.