I agree that Selene has moved out of focus. Part of this has to do with the normal life cycle of a major expansion, where we don't grossly overgear the content and see more value in Eos' defensive and healing capabilities; the other part is that Selene has become kind of...lame.

Her signature buff is still fairly unimpressive, her AoE Esuna is a cool ability that is rarely useful in practice, and her Silence is incredibly niche because of pet AI lack of instant responsiveness to player commands. Even back in 2.x we only really used her because Eos was just that unnecessary for most things; her buffs weren't all that amazing, but they were preferable to both overhealing and nothing.