I think Hawke had more going for them besides the neutral dialogue changes.. the whole group was just kind of a band of adventurers. It was probably easier to write that than the overblown "leader" nature of Shepard or the Inquisitor. I mean, it's just a lot more personable in general to be Hawke than some "official". Plus, Hawke had detailed family life to flesh things out even further.
Yeah he had - sadly enough (I hate(d) Carver with a passion (did never get Bethany because I was a mage...but I guess I wouldn't have liked her and her insecurities and self-hatred...oh, I am a mage, I need to locked up in the Gallows...**** you BETH (that's another thing: You couldn't stop either sibling from leaving...Beth ends up in the Circle (or a Warde or dead of course!) and Carver ends up a damned Templar (or a Warden or dead, again)!) - I didn't kill him (I knew you could), but him turning into a damned Templar (an enemy by choice...****** religious pricks - like only very very few of them (Alistair who was luckily rescued from becoming a Chantry-Drone by the Wardens, Cullen who left that live and his mage hatred behind, Cassandra (seekers are Templar-Oversight/Internal-Affairs after all!) who isn't a drone either...other than those? Well, there's very very few I would consider working with...most I'd be glad to just get rid off (banish them, kill them, lock them up - whatever, as long as they are gone!)) was a low blow IMHO...yes he came to his senses in the end, but still...also the family story was the weakest part of DA2, not that the rest was all that great either (it wasn't bad, the game is certainly better than DA:I in a lot of ways - but both are lacking when compared to Dragon Age: Origins!)) Hawke had a family 
Didn't like the family story back then, didn't like the one in Fallout 3 and didn't like the one in 4 either, so I guess I won't like the family story in ME:A either! 