Is this an even reasonable topic? I think the chances are slim, but you will never know in till we try.
The problems now are -
Shadow Form - You need additional skills to stay alive. (Old, invincible to all except signets + touch skills)
Dhuum/Skeletons/2009 Halloween update - An extra enemy + additional time to complete.
Sliver Armor - Longer to kill.
Damage Buff - Nerfed. Enough said.
Activation times - Added a stack.
Mindblades - They now how Leech Signet.
Now, changing all these back would result in lots of Speedclear changes. Although it's easy to make a cap to just UW.
A possible theory I advised would be :

Just like the Normal Mode & Hard Mode buttons. PM stands for Pre meta. This function will only exist in the 3 Underworld access points. Try using it to gain entrance to FoW, or outside the outpost will not allow you. A solution like this would not change the whole entire game again, and you will still have a chance to do UW old meta if you like. Click HM, then PM button, or unclick it to take it off.
Leave a comment on what you think, and a +1, or -1.