I dunno why I kept killing them. It was pretty annoying and frustrating to chase them across half the map. With the slow casting of my main damage spell, most casts would miss as they ran and ran and ran and ran and ran and ran and ran and ran and ran and ran away from me.
I finally questioned why I was doing it and, lacking any good answer, stopped. I'm much less frustrated now, and I complete my exp runs in as little as half the time. The AI on some monsters in this game really needs to be reworked IMO.
I am a CM wizard with an interdasting primary spell, I use shock pulse / living lightning, which has the benefit of moving the same direction they run, hitting them the whole time. It makes it much less painful.
As Archon I have no problems with them, but I don't farm Act 3 as CM in part because of those elites, as well as the other ranged mob types in Act 3 that can be very annoying for CM builds. Also, I'm too stubborn to skip mobs, even reflecting teleporting firechain vortexing phase beasts that kill me very easily. I have to get my revenge...