I guess the main Reason for the change is that, indeed if you are very lucky (just ignore the % and think of the possibility) you could get 4 turns in Total without the change Round 1 - Enemy Turn Round 1 - Your Turn, you roll Triple 6 Extra Turn (now you wouldn't get an extra turn with the triple six but what happens next is Round 2 - Roll initiative, if you win Round 2 - Your Turn, you roll Triple 6 Extra Turn Round 2 - Enemy Turn Even if the odds are almost 0% for this to happen it still is possible and 4 Turns of you, in which the enemy can't do anything but cry is REALLY overpowered This could Win a game by just 2 very lucky rolls
There's plenty of horrificly overpowered stuff if we assume the optimum scenario is realistic and happens on even a vaguely frequent basis. 40 skinks could theoreticly kill virtually anything they're faced with in a single turn if the stars align, but nones going to claim skinks are overpowered, or even powerfull, because of it as the chances of it happening are negliceble. Getting two turns in a row like that with the EoTG happens 1 in 46656 times. Even if you field multiple EoTG's it'l take you thousands of games to see it happening. Balancing around an option that can happen once every few thousands games is both impractical and pointless. So I doubt that's the case. \ Also if you get that absurdly Lucky you deserve the win, just like how when your skinks have the day of their live and kill of nagash or archeon in a single turn you deserve it.