There would be 1 reason why I would log on to any such server. Do to original AV! ok and maybe do green dragons + original kazzak and raids if I had the time. other than that no. I would also play a warrior and not a shaman. I hated having to play a healer when I had no intention of being a healer when I logged in for the first time!
It would cost blizzard a fair amount of time and money to set this up despite what people say. The only way I could see it coming would be if we saw realm merges and any free'd up resources from that "could" be used to give these servers a try. but I doubt the demand is as high as people make out.