things i'd like to see

No one says pre-teens don't exist. I'm saying we already have them in the game, except they are called children. Perhaps the devs should rename current children to pre-teens (like babies were renamed to newborns) so you would be happy. 

Preteens are children aged 9-12 (some sources say 10-12). That's how old the children are in this game. They are preteens. If anything, we're missing younger children stages like preschoolers and children who are just beginning school. 

I have no idea what Brady Bunch is. Google tells me it's some American TV show? Never heard of it, sorry.

No we don't a child and a preteen are different preteens goes through changes like puberty their more moody because it's in early stages of puberty, they are more developed body changes like Body Odor, voice change, attitude changes something they once liked as a kid they may not like anymore. At this age they tend to not listen to authority but listen to the peers because they "know" best. They are more aware of fashion especially fashion brands then they were kids. I don't condone it but bullying usually starts around this age group especially if you don't have the latest and the greatest or still hanging around parents. Preteens could do a little more then child like early stages of cooking, play basketball, sit in the hot tub, have a social bunny, but also they still play or hang out on the playground equipment, play critters, play marbles. They can do stuff that the kids Lifestage can't do and also do kid stuff that the teens Lifestage can't it's the in between Lifestage like infants, toddlers and YA were introduced throughout the game series. Even InZoi and Paralives are including the on between Lifestage eventually in their games so why not the Sims? Especially since some Simmers have been asking for it.