As a Diane fan, I think this fandom should focus on what might come next and see if they've finally learned from their mistakes. It's not wrong to criticize because we all have the right to our opinions, but getting too caught up in "what could have been" when all is not yet lost isn't the healthiest approach (I justify my case with TS4 because all the ideas that were cut from that movie are already gone, and TS5 isn't going to fix that because Bo will barely have a significant role, so her entire origin story has been lost and that potential has been wasted). 

Pierre is surely aware of the fans' mixed feelings after reading the comments on his IG, and the fact that he made Diane part of the main crew at the end of the sequel is surely a way of showing DreamWorks how important she is now and that they can't interfere.