However, I do think that, for a reasonably small amount of effort, Blizzard could make a version of the current game that reasonably approximated the original experience. I'll call such a server a "Legends" server.
A Legends server would have:
- A constant Legends debuff which reduced health, damage done, healing done, and XP gained by about 50%.
- Looking For Group/Raid disabled
- Heirlooms disabled
- No server transfers
- No cross-realm zones
- Battlegrounds/Arena disabled
- One character per account per server
- Pet Battle Queue disabled
- No Starter Edition accounts
- No Death Knights / Demon Hunters, classes which start at a higher level
- Black Market Auction disabled
I think that would be enough to create a Vanilla-like experience. You'd still have the same quests, classes and talents as the regular game. But a lot of the elements which Vanilla champions say hurt communities would be disabled. I also think that the amount of work required to create such a server would be relatively low.
You'll note that the one thing I did not add was a level cap of 60, or disabling access to expansions. I think that will be very buggy, and end up eating a lot of QA and bugfixing resources. It would also require class design to be tuned for a cap of 60. Raids at 60 would have be tuned again. As well, there is gear from the expansions available at 60 that outstrips raid gear, and trying to keep that gear out of the hands of capped 60s might be a lot of work.
I think trying for a lower cap is simply unfeasible. Better to simply have the same game as the regular servers, just with some added restrictions. The Legends debuff could be reduced at the real maximum level too, if that turns out to be an issue.
I think a compromise like this could worthwhile for Blizzard to experiment with. Personally, I think a lot of people would roll on the server, but most would soon go back to the regular game.