I agree that the only reason we see Bill and Katie is the actors. They are popular even with the lack of airtime. Maybe Winsor got another job or won't be anywhere near LA, I hope we don't get Thorne's death at Christmas.
Laura who was adopted by Brooke was a victim of abuse as a child on All My Children. Kim Brady was molested by her Uncle Eric on Days, this happened off screen as we only met her as an adult. (Of course, the fact that Eric Brady is named after an abuser is problematic.)
Justin and Adrienne were never as big as the other 80s couples even if they had the amazing Greece remote to wed. I wonder if part of it is how for so many viewers the actors are well-known and/or loved for other parts that aren't these characters. Having Adrienne go to Kayla, and then have no line from Kayla stating that we'll have to check my kids too would have made sense since Patch went out of town. And that eventually this info has to get to Abby and JJ as they're Jo's grandchildren. The idea that only Adrienne knows about Jo is weird.
There is one person who ran towards the shooter in Oregon, but he had been in the military. He knew what he was doing in a war zone. Some people may go into shock and cannot move, that has to be a possible behavior some exhibit.
It would make more sense if it was Jennifer, but I figure it is for drama reasons also. I could understand if Jennifer and Hope had a scene together, and Jennifer had to decline because of the mess with her resigning from the Horton Center. Since Hope is a cop, having a family member who has been rumored to be involved in drugs standing up for her could be seen as problematic professionally. Then the choice of Kayla would make more sense. I figure it has to do with Bo being missing or Steve returning etc.