Missing critical strike chance

It is really disappointing that the Minion Instability keystone passive, Avatar of Ice skill and Avatar of Flame skill have AOE effects in death but these effects have no chance to be a critical strike. All of these AOE effects are pure elemental damage and would be a lot more attractive if they could be a critical strike. Does anyone know why these are like that?

For avatar of flame, if it could crit, that would enable damage to "double crit" (crit once, killing the mob and causing the ignite, and then again upon applying the ignite).

I'm sure someone would immediately find a way to abuse it against high-HP mobs and bosses to kill them almost instantly with the ignite.

As for AoI/MI, I'm not sure

Thanks for the explanation. I already knew all of that. . .I was just wanting to verify that there is no critical strike chance on those effects.

You see, if you want a clarification on a subject, don't ask, tell. If you emphatically state one side of an issue as fact on the internet, you will quickly find out if you're correct.