I think for me the biggest sort of...turn off, if you can call it that...is that people seem legitimately to feel that Cole is just adorable. Poor little guy who just needs someone to love him...and it just really, really weirds me the **** out.
Now granted, maybe he'll be less Mary Bell and more misunderstood teen dreamboat when paired with a voice but....
I think he's an interesting character, no offense to DG or anything. I just don't see why people would want to give him cuddles.
I don't know if it makes it more or less weird for you, but as someone who wants to wrap Cole in a blanket and feed him soup, I feel the same way about Zevran, Merrill and Fenris. Merrill is a blood mage, and Zevran and Fenris have each killed far more people than Cole has at the end of Asunder - and with far better understanding of what they were doing.
Many of our Dragon Age companions have been guilty of cold-blooded murder, and a few have made a living at it, but that doesn't mean I can't feel sympathy and affection for them. (After all, we spend most of the game killing people and things.) Cole can't help what he is, and he doesn't even understand his own nature, which is more excuse than Zevran has, or Leliana in her barding days.
Mind you, that doesn't mean I condone his actions. I hope I get the chance to give Cole a hug, make him a cup of hot chocolate and tell him to put the murderknife down unless we're in combat.