They shouldn't remove all timers, especially on specific encounters where timers can be used as a DPS check. However what is poorly designed is that the timer is for the whole fight and not a simple enrage timer, where the clock starts ticking only when the boss got engaged.

That would make more sense and solve the cutscene issue all together. Same for dungeon or everything, timer should only starts once someone started to move forward (just allow couple of steps before the timer kicks in).