Are you actually being serious? The amount of support Soldier and Shaman gives to AAR is nothing compared to Demolitionist. Flashbang and Blastshield both are great contributors to defense, and while you can argue that Shaman and Soldier boosts defense better, it is still horribly inefficient and unwise to take a class just for 2 skills and its mastery points. Compare to the amount of relative damage potential from Demolitionist such as Flametouched and Vindictive Flame, it really isn’t even worth a debate on which class supports AAR the best from the three. Sure, extra defenses are always nice, but that is completely dwarfed by the damage increase from Demo.
Arcanists do not lack defense on their own, with their Maiven’s Sphere of Protection and Mirror. You can argue that the caster armor they usually wear makes them lacking on defense, but they are not tanking nearly as much as traditional Soldiers or Shamans. There is a big difference between statistical and practical survivability.
At this point, I am pretty sure you have not played any other builds, or even bothered to learn about them. If you have, you should know that AAR does not have damage to spare, especially your specifications. Your standard for “good” damage is very very low; is “good” damage, to your definition, being able to kill dummy within 10 minutes? Log’horrean within the hour? Just able to kill Mad Queen at all? At 90% hit chance, what are crits even?
You should come to know that many many other builds trump AAR in single target damage. Builds like DW Spellbreakers or Saboteur that can kill dummy in around 23 seconds and Mad Queen within 10 is by far superior. Other examples include builds like Savagery Ultos Elementalists, DEE Witch Hunters, or even officially dead Blademasters and many many others doesn’t even bat an eye to the single target damage, or the lack thereof, that AAR is doing. Not to mention all of the builds above, except for maybe Blademasters, have superior AoE effectiveness than AAR.
I think the misconceptions you have there comes from your lack of damage, not the lack of defenses. Just because you are dying frequently doesn’t mean that increasing defenses is the way to go (it usually is but not in this case). You also have to consider that if you kill the enemies faster, your effective survivability goes up from not tanking as much enemy hits, and you certainly doesn’t have surplus damage when it comes to AAR. This misconception is probably why you like Soldier and Shaman over Demolitionist. Scary.
OP is wrong to stress that damage is not a problem for AAR; however, that still doesn’t justify the need to pick a completely useless, albeit tanky, second class like Soldier or Shaman.