I'm not quite sure actually.
Carlisle is mentioned quite alot. Like in all books and films there are the bigger parts and the smaller parts.
Even though Esme's part is only small it's still an important part.

I've wondered that myself. Her part was already too small in the books, and they've cut her even more in the movies. But she's important. Especially because of her suicide attempt and a certain event in NM. I can't believe that they cut out her talking to Bella about that during baseball.

I'm hoping that Stephenie has something up her sleeve and that she plans on writing a book about Carlisle and Esme. I would be eternally grateful if she did that. I don't know enough about them and their past, and their relationship. Here's hoping. =]

the answer is simple:stephanie mayer is stupid

It always depends on what way you look at it. Of course she doesnt get mentioned that often, but she is very important to the family. And then to Bella and even Jacob... so i guess over all her part isnt that little :D

because she is a mom and in most books and movies a moom is not really in it and we dont know much about her so we dont know what to do with her