I understand what you are saying, but I don't think a match here or there with other characters will make that much of a difference. Yes, there will be some strategy maximizers who may be annoyed because every single second isn't being dedicated to that one specific character, but that already happens anyway. We are required to use required characters that we rarely use in PvP or PvE all the time. How often are you choosing 3* Blade? Yet, when his PvP pops up everyone uses him. Even if the desired character cannot be utilized in a specific PvP event, that character can still be used in all other PvP and PvE events providing plenty of opportunities to take advantage of the suggested mechanic.