I think it's enough that we've got characters such as Maud and Starlight and Discord getting more development and screen time. Sure I'd love to see more of Bon Bon and Lyra, but just because there are other characters in the spotlight right now, it doesn't mean that we won't find out more about them in a future season. By the way things are going with a Season 8 confirmed, there's a lot more of this show to come, so who knows we could quite possibly find out more about the background characters. I think of the development of secondary characters as being a step towards that.