To an extent I can understand why people who don't like qunari wouldn't want a qunari character to be likeable.
For me, it's the chevaliers. I hate the chevaliers. Not on moral grounds like some people here, I just dislike them. I feel that they should be portrayed as a decadent and declining order, a shadow of their past glory, and as far more style than substance. Competent warriors, sure, but no where near as good as they think they are or proclaim themselves to be. That was my vision of what chevaliers should have been.
Bioware disagreed, and felt that chevaliers should live up to their hype. So every time I see or hear about a chevalier being an exceptional warrior, I grit my teeth a bit. "They shouldn't be like that." I tell myself. "They shouldn't be that good." It's the primary reason I hate Michel.
I imagine it's the same for qunari-haters who never the less find Bull likeable. He challenges their preconceptions about what a qunari should be. He doesn't fall in line with their idea, what allows them to hate qunari.
So, yea, I get it. Don't agree in this specific case as I rather like the qunari, but I get the mind set.