Not necessarily perhaps the future didn't have enough people her [how she appears] age that she could be friends with and even if she did maybe NQS wanted Chibi to train with the inners and learn to be a sailor senshi as she herself did with Luna in addition to meeting good friends plus getting an education, having Ikuko help in raising her is also a plus, maybe the past has something the future no longer has that could help in raising chibiusa like the normal civilian life, maybe in the future everyone treats her like a princess and that makes it hard for her to connect with people normally, maybe she has to act all proper in public, I guess in the future the only time she feels normal is when she hangs out with pluto. In the past she could be more casual thus happier which when you think about it is what parents want, their kids to be happy