I don't credit Stephenie Meyer with enough intelligence to have figured out this line of reasoning. I think it's most likely that Meyer created situations so that Edward could save Bella, and due to either lack of imagination or inability to notice, the preponderance of dangerous situations (and especially dangerous people) ended up very high - high enough to give smarter people ideas like violence is just more common in that world.
That said, my views on Twilight are extremely biased by my social group.
My idea that violence is common in the Twilight world is not primarily fueled by danger to Bella in particular. I was mostly thinking of, say, Bree's death, or the stories about newborn armies and how they're controlled, or the fact that the overwhelming majority of vampires commit murder on a regular basis.
I've often had half-finished LW post ideas and crossed them off for a number of reasons, mostly they were too rough or undeveloped and I didn't feel expert enough. Other people might worry their post would be judged harshly, or feel overwhelmed, or worried about topicality, or they just want some community input before adding it.
So: this is a special sort of open thread. Please post your unfinished ideas and sketches for LW posts here as comments, if you would like constructive critique, assistance and checking from people with more expertise, etc. Just pile them in without worrying too much. Ideas can be as short as a single sentence or as long as a finished post. Both subject and presentation are on topic in replies. Bad ideas should be mined for whatever good can be found in them. Good ideas should be poked with challenges to make them stronger. No being nasty!