I don't know that "odious" is a good term, and yes he was the King of Durin's Folk. However, Dain appears, at least to my eyes, to be a more respected and rather more grounded individual.
And then there is the fact that he was the one who actually killed Azog which made him a hero at a young age. Thorin didn't have much (that we know of) in the way of accomplishments to compete with that.
Mostly at this point I am just throwing theories out to rationalize the choices Tolkien told in stories to his kids that he later incorporated into his larger mythos.