Blizzard for me with 18K dps sits around 1,337 (yeah I got it to tick for that much!), to 1,800 roughly, yeah it's pretty pathetic. The reason why it is there is so I can SPAM THE HELL out of it and it'll slow and I don't even have to be on the screen for it to go off. Many times I will drop it behind me and keep running.
When I came up with the build I was looking for a cheap snare, damage would be a good plus but wasn't the intent as I was going to be saccing life for damage.
Also the reason behind the arcane hydra, is AOE. I drop it on the packs on the skeleton king and they are killed in a second with blizzard raining down so they can't get close to me, so I can get back to killing SK.
What kind of damage are you running? The champion packs range from 1-2 minute kites, to 4 minutes boarder-lining enraging due to shield/health (stupidest combo EVER)
I never was a fan of illusions tbh, so many times I would pop it and they would run with me instead of stand there and be a distraction.
I'm sitting at about 25k DPS, pretty much the same as you since I have Magic Weapon. I generally find champion packs take about the same time too. Occasionally I run into a really weak group (Relatively low HP and no gimmicks like Vortex or Mortar) and they drop almost as fast as a normal pack of mobs, with minimal kiting required. I agree too, Shield/Invulnerable Minions are the most annoying attributes ever, I skip the latter sometimes if it's just too troublesome to take the time to kill.
The main reason I take Mirror Images in addition to Teleport is because it also breaks you out of snares and roots (not Frozen though), for additional insurance against bad RNG. Sometimes against Mortar + Jailer or something, you Teleport out and immediately get jailed again. Sometimes you get bad luck and run into rare fast mobs (leapers or something) with the Fast attribute and they will nearly always be hitting you since they plain outrun you, so you can cycle Teleport and Mirror Image while kiting and always have images around.
The images from both also give me a bit of breathing room to DPS if the enemy decides to focus on them. What I like best about Fracture Teleport though, is that it's a 'free' Mirror Image every time you teleport.
Normally after teleporting you are vulnerable for the whole 15 seconds unless you invoke another cd, but those images occupy the enemies' attention for the 7 seconds they are up. It's nice to have them as cover for a period of time while you wait out the Teleport cd. I do agree though, images in D3 aren't as good as the ones in WoW at drawing attention away from you - the mobs are smarter.
Incidentally, I'm a big fan of Seeker Magic Missile as well, I was using it before I swapped to Arcane Orb for better burst. You can do some funky things like shoot around corners and walls while you stay out of line of sight. Also, if you consider that we're all human are just plain miss with spells sometimes, it's not really a true damage loss over Charged Blast Magic Missile.