Explosives should spawn for a specific random player each time and only that player can kill them. Good dps already help kill explosives, but most dps are not good. And with all the “Orbz er healer jerb!” parroting on the forums a lot of dps completely ignore them.
The problem is every failed mechanic or affix falls onto the healer or sometimes the tank. As long as the punishment for failing stuff is simply more damage, it will always fall on the healers. We need affixes or mechanics that punish dps for a change. Change spiteful to apply a 50% dps debuff and watch how fast dps players stop face tanking them.