No, I disagree, I think it is important; it's a massive shift in the status quo, if anything it's more important now to show even a glimpse of how some characters got from A to B in terms of thinking because it further informs why what's going on now is so important and gives us all proper context for how the characters are feeling/thinking.
If anything, it's just lazy to hand-wave it away and unhelpful; it won't help readers who feel that disconnect in any way and, therefore, won't stop wonderings about how/when/if this new direction will deviate.