The problem with 21122 is that the opponent doesn't have to read in order to beat the cancels. If EB doesn't grab then the opponent can just crouch block until the grenade or Stance come out. Stance, both 2 and 3, can be poked out of easily and doesn't have a flash like exSG. If they don't want to risk it then they can crouch block the whole string and never be at a disadvantage.
Sure, people that don't know the matchup (don't crouch block) can lose to EB. Anyone that knows enough to crouch block, however, has eliminated EBs gameplan almost entirely.
Furthermore, with the new stamina drain EB can't keep pushing them back and rushing in anymore, and his overhead is 23 frames now so he can't Oki. You can grab and knock them down, but you can no longer force them to read what you will do on wake-up. If you knock them back you will have to use all of your stamina to get in, and you won't be able to follow up with a combo if they get pushed back by any combos as you won't have the stamina to rush in again.
Gunslinger is better than the other variations by far, but the weaknesses are glaring and easy to take advantage of. When EB had tick throws he could force opponents to respect 21122 and all its options, but now it is pretty much just lows that push the opponent back and make EB super vulnerable to counters.