If the retreat *on always worked then how will the whales have fun in the game?. As of right now only arena has the constant retreat feature and that's because the BP is always equal in that mode. In every other mode the players with less BP ALWAYS retreats unless it's someone famous in-game they know like a youtuber. Therefore if they enable the retreat *on then 90% of the pvp matches will end in retreats because we all know how ''fair'' the match making in this game is. I think matsuri also has permanent retreat *on but it's use is discouraged by the fact that you can't use those ninjas again if you retreat (you can revive them but only once).

TL;DR pvp will become retreat simulator if they make it permanent option in pvp because the system is not fair in match making and no one wants to get beat all the time by unfair High BP.