There really should have been an AoC or any instance giver to the old original Sleepers Tomb with original warders and Kerafyrm, with original loot tables. This has nothing to do with wanting an original Mask of Tinkering, promise.
Less a missed opportunity and more a design choice, the devs could have done this already if they wanted to, evidently they did not and had reasons for not doing so. I suspect they wanted the pre-awakened sleeper phase to remain special and limited by the same constraints as it has had historically. Players as a community actually switch the server between the two phases so its the players who already have the power to choose here, if they can resist the temptation to shut the door at least.
I agree with OP. I never got to see the original so it would be fun to jump into an AoC and see this thing that is literally never going to happen again on live servers.