Elder the Dwarf
Maester
Putting aside the marketing argument, the other arguments regarding the success of the series are always some variation of the argument that the readers of the series are not as smart as the person making the "witty" or "insightful" commentary about how bad the series is. Such arguments can and should be discarded out of hand, because it is demonstrably false that the fans of the series are a bunch of idiots. Quite the opposite, in my experience. The argument that the readers/fans are just stupid stems from insecurity and/or jealousy and/or the need to be trendy, in my opinion. I know some very smart, well-educated (and yes, well-read) people of all ages who enjoy the series a great deal.
NOTE: Nyx - you are absolutely right. It is the popularity that draws the ire of people, plain and simple. People might like or dislike it, but if it weren't so popular and loved by so many people, you wouldn't see the really irrational, frothing-at-the-mouth bashing of it. Twilight haters are even more obsessed with the work than the hardcore fans.
On the first point, I agree with you on all those points except one. There may be well-read people who Twilight, but the vast majority of the Twilight readers that I know (talking about 99% or so) are the same people who are reading the Clique novels. Which is fine, those books just aren't my cup of tea. Now I am not going to insult the novels because I have never read them. I can't say her writing sucks because I have never read her work, mainly because her plots are not something I would enjoy. However, a 30-second commercial spot is enough for me to say that the movies are beyond terrible.
To the second point, I'm not sure how well the word duh will go over on a writers' forum, but it is applicable here. In any area of life, nothing draws mass hatred unless it is popular. I hate Lebron, I hate dubstep, I hate Lil Wayne, and I hate Justin Bieber. Notice that none of these is a garage band or an average high school athlete from Michigan. Why? Because bad isn't a really strong reason for hate. Neither is terrible. Overrated is. Popular for no reason, or for bad reasons, is a much better catalyst for hate. So don't play that ridiculous card. If her books weren't popular, there would be no chance to hate it. I could write the single worst book in the world and nobody would hate it, or even care, unless a bunch of stupid people went to the stores, bought it, and made me famous. And you have to be more than famous, you have to have a following. Notice that I said I hated Lil Wayne, not Soulja Boy or Waka Flocka. Wayne is clearly better but because, despite their fame, almost everyone I know accepts the fact that both of the latter two are terrible, I just don't care about them. However, I have a lot of friends that love Lil Wayne, and I think he is awful, so his music stirs a passionate hate in me. I personally didn't know Meyer's name before this thread popped up, and I don't care about her writing either way, so I can't hate it.