Betty is written really well and acted adequately at the best of times and terribly multiple times. The show shoving Betty to the peripherals can only be a strength in my opinion, since this show is more and more about times changing, it's natural that Betty gets phased out, she's a dinosaur culturally, and she's one of those characters who is a comment about how people get left behind and forgotten by a culture rapidly moving forward. Her true value in these latter season(this season and onwards) should come from being Sally's mother, actually, since the show is more and more about the young people. Like many people in that era, Betty has been made almost irrelevant. It's a good thing.

However, she might be more prominent next season because her absence might have more to do with January Jones than the writers wanting to do less of her.