Poor Bethany...it does seem she gets very little love in these forums. Just because she is pretty, some people think she will be uninteresting. I think that is why she gets little love. She (in my opinion) is the best looking character model so far. Not to say that the others are ugly. They aren't.
I think that good looks, especially a big chest and an outfit that helps display that big chest, is too quickly turned into: "She is a shallow character, a "floosy", and only made for horny male teenagers." This has always made little sense to me. I think sometimes a big chest is quickly equated to many negative things. However nice legs on a girl wearing short-shorts is viewed less negatively than a girl wearing a shirt that supports her chest well. Personality is not based on looks. Wanting to look sexy does not equal wanting to have sex. Wanting to look sexy could very well be just personal empowerment. Or maybe Bethany is into style.
Anyway, that is my take on why Bethany gets less love. I think she is quickly passed off as nothing more than good looks.
Switching topics...
I think that in personality, Bethany and Carver will be rather different, like polar opposites. I see an interesting amount of potential for these two when it comes to interacting with Hawke.
My theory is:
I see Bethany as a quiet, sweet, young sister. She will be less confrontational. However, she is a fire mage, so she will have times where she takes the initiative and becomes more outspoken. I think that if there is a Mage-Templar conflict, she will make a warrior/rogue Hawke think twice about siding with the Templars, either by being the kind younger sister, or "flaming up," metaphorically, and getting really angry at Hawke for even thinking about siding with the Templars.
I see Carver as someone who is practically always outspoken, always challenging you. He will have very strong opinions and voice them constantly. He might even be against Magic, forcing a mage Hawke have to either be really diplomatic with him, or confrontational(Friendship/Rivalry thingy). He might side with the Templars and try to persuade mage Hawke to join his side. He might have tons of compelling arguments too.
Anyway..that's my theory.
Looking forward to Dragon Age 2.