Wiz/Sor have always had to balance damage and aggro carefully. High damage spells that heavily damage more then one enemy (like Wall of Fire which you can kite survivors through), or single target spells that almost guarantee a quick death are great since they kill enemies without drawing too much aggro (since the enemies are too dead to worry about aggro). Of course, spells that both instakill AND hit multiple enemies are even better of course, assuming they hit (failing a wail against 2-3 orathons is a Bad Thing (TM)).
And some spells, while useful, fell into the dangerous area of hurting multiple enemies, but not killing them. Fireball is a great spell, dealing lots of damage in a good range (area). But if it does not kill the enemy outright, you are going to be attacked by some very upset enemies.
Chain missile, i am afraid, now seems to fall into that category, and on the worse end of the spectrum as well.
Before the update, where force enhancements were lower and/or harder to max, Chain missile was a nice clean-up spell. Even an un-upgraded CM (no max or otherwise) chain missile would hit lots of enemies for low damage. If their were multiple enemies, it might kill off one or two and hurt the rest, all while not dealing enough damage to get aggro. If there were only 2, one would get hit for pitiful damage while the other would take 200-400 damage and usually (at that level) die. In either case, if one or two mobs got aggro it would be easy to finish off as it ran at you. And best of all, since it was unblockable, you didnt have to worry about getting the aggro of a mob with reflex saves.
However, yesterday i was playing in crucible at low (wiz) level (doing crucible at normal, with a level 10 wiz/2rogue) and since i was playing an evoker, i spent most of the time throwing out 2 sp Magic Missiles and Force Bolts (after all, i had few damage dealing level 5 spells, and no level 6). Delt reasonable damage (i think i even had first or second place on kill count) and never ran out of mana. But EVERY time that i threw out a chain missile to help the party drop the enemies faster, it cost something like 50 mana and got the aggro of every enemy in the fight. At least twice i only survived because the enemies were nearly dead, and the party could help kill them while i fired off force missiles and Chain missiles as fast as possible to kill the hobgoblins draining my hp.
In summary, I love all the force spells when fully upgraded, but chain missiles has become a VERY situational spell, that should be used only when there are very few enemies to concentrate on (and to fight off if they dont die).