I started reading the series the end of my junior year which was May 07ish I would guess and the people at my school weren't that crazed about it yet. Eclipse came out August 07 and it had definitely become more popular. So I would say sometime in the summer of 07. It was definitely as popular...
To be honest, I don't know. Every point you've mentioned is entirely true. I understand hardcore fans of Twilight defending it because they love the books or the characters but to say that it is a better written book is ridiculous.