Even the actress who played Beth agrees that it made less sense to write her off this season after investing the time in developing her character
I think we can't judge the death of Beth until we see how it plays in the plot line for the remaining episodes. Deaths in this show are either just to lighten the load of story arcs, or as a catalyst for more growth.
Carol doesn't exist without Ed's death
Carl and Rick's character development was closely tied to Shane and Lori's deaths.
Andrea's slow development came at the death of her sister.
Daryl grew quite a bit after Merle died.
etc., etc...
Beth was developed as a deeper character and even formed a relationship with Daryl for the very purpose of being killed off. She never existed in this show as anything more than a supporting character - and her role is to do what supporting characters do, offer springboards to the main characters and plot lines. Her death is going to play out as her biggest role, and while I feel for Emily Kinney having to leave the set and change her life quite a bit, Beth's legacy is going to be felt for quite a while within the group - probably more than most.
If you recall, the group as a whole hasn't had a chance to grieve after the prison exodus. It's been a road warrior kind of lifestyle since then. Beth's death and the elimination of the threats surrounding their people are going to offer that long-needed grieving period. I imagine the writers have take a more deeply emotion, character-driven, approach with what's coming after the mid-season break. The threats are gone, for now. They don't have the excuse of a constant threat, or of separation, to fuel their escapism. They're going to have to deal with some untended things. It should be good.