It's so bad now, their method of letting use openers more requires not being in stealth.
Doing too much damage in one hit is OP. Etc.
The only reason I fell in love with Subtlety in the old days was because of how stealth oriented it was. Sneaking around and getting that one big Ambush off was satisfying. Getting a few links really hurt, because your single target damage wasn't that good.
All they would have to really do is make Master of Subtlety matter again. Have it break instantly when you leave stealth, and have it be a very huge increase in opener damage. Can even make it have Cheap Shot do (not very good) damage. Could add a debuff in PvP only like "You have been recently ambushed! Your perception has increased temporarily...", making further Ambushes do 60% less damage for 6-8 secs. That would prevent vanish spamming or Rogue stacking.