There's a number of reasons I made my monk Iksar. As you said, the AC bonus is pretty hefty and I was using him as a tank in my 6 box crew. You can also start the Shackle quest immediately without having to dick around with faction work on a Human. Do not rule out the Regen bonus as well. With Fungi Tunic, Fungi Staff, and level 60 you can regen pretty quick.
Regen Table:
Both Iksar and Trolls have higher HP regeneration rates (per tick):
Level 01-19: 4 sitting, 2 feigned, 2 standing
Level 20-49: 6 sitting, 2 feigned, 2 standing
Level 50: 8 sitting, 2 feigned, 2 standing
Level 51-55: 12 sitting, 8 feigned, 6 standing
Level 56-59: 16 sitting, 12 feigned, 10 standing
Level 60: 18 sitting, 14 feigned, 12 standing
Comparatively, these are the HP regeneration rates (per tick) for all other races:
Level 01-19: 2 sitting, 1 feigned, 1 standing
Level 20-49: 3 sitting, 1 feigned, 1 standing
Level 50: 4 sitting, 1 feigned, 1 standing
Level 51-55: 5 sitting, 3 feigned, 2 standing
Level 56-59: 6 sitting, 4 feigned, 3 standing
Level 60: 7 sitting, 5 feigned, 4 standing
Also to note: it is pretty handy as an Origin point during Kunark for mobilization if you are far away from porters. Cabilis is relatively central.