I personally believe original WoW and TBC was fun but that's just my honest opinion. WotLK though was pretty much the downfall for the fun experience and the value of the game itself, speaking out of personal opinion though... 
  
I would enjoy it if Elysium managed to create a TBC server alongside with the original WoW server, it'd for sure boost the player population base, so I see no point why they wouldn't do that at this point. But I agree the costs for hosting and such would be the only downside I suppose. But I see other people hosting TBC servers without any issues whatsoever, so I can't really see why it's a money issue generally since hosting is fairly cheap these days in various countries. I do not see it as a major threat for making a TBC server happen. 
  
I do know that there is a ton of TBC players out there that would want to see a TBC server happen for Elysium, the question is just when those players will see this thread and respond with same demand as me. Don't get me wrong. I like original WoW too it's just that TBC was my goto expansion.