Well, you can get to the cap on elemental resistances pretty easy on templar even without that halfkin bonus.
There is a class talent that can give you +10% all ele resists, so that's not really a problem on templar.
So, basically, if you get the class talent, heroic trait, and the passive on halfkin, you'd be starting with 20% in every elemental resistance, more if you get some crafting achievements.
All that really means is that you don't need as much equipment to get to the max resist.
The different amount between races doesn't really matter if you have enough resist.
On the other hand, you have to look at each race's talents and compare:
Ursun, for example, takes 15% less crit damage, which I think is pretty good. (note, halfkin has that on knight)
Zumi and Anura's passives are boosts for mace, which don't really help you tanking, besides aggro and such.
and humans get shield bonuses.
Anyhow, halfkin templar should be fine, even with less hp.