I rather suspect that the reason Breaking Dawn was... the way it was... is because it's really about nothing more than Meyers coming to terms with her unexpected and sudden fame and riches.
Hear me out.
Bella (Meyer) wants to be a vampire (writer). "Oh, no!" moan the other vampires (writers). "That's really hard. It is NOT all that it is cracked up to be! You will be feral (poor) for a year (years) and even then, only with the greatest willpower (luck and perseverance) will you be able to avoid chomping on people (starving in the gutter)." And other stuff about vampirism (having a compulsion to write).
But darn it all, Bella (Meyer) wants to be a vampire (writer) anyway. So, she gets bitten (sends her book out). And lo and behold, while it is painful (it is scary), it lasts only a short while, and suddenly, she's perfect! She has no period of crazy "I-eat-your-face!"-ness that everyone else does! (She's an instant best-seller!) And then the gifts continue: She has awesome mind powers! (Fame! Riches!)
The only problem is that the Volturi (fill in the blank: critics? the internet? the mean fans?) don't like her--and the head of the Volturi (Stephen King) is SO TOTALLY MEAN TO HER (doesn't like her writing, and publicly), and everyone wants to kill her crazy sparkly hybrid unnatural baby (the whole series).
And then pedophile werewolves fall in love with her baby.
(Oh, wait: TwiMoms?)
Okay, anyway, there are some goodish vampires (people on the internet, the ones who don't leak copies of Midnight Sun, anyway) who come in and defend Bella and the sparkly baby (Meyer and the books). They get the mean Volturi to listen to them! And explain how awesome sparkle-babies are! And then the Volturi just go away, totally defeated by logic and Bella's mind-powers. (This hasn't, to my knowledge, happened yet.)
And of course, I actually gobbled the series like the crack that they are, and have defended it, and even liked it. But I did not find any satisfaction in the arms of Breaking Dawn--and I think the above is part of why.