While I can see where more family play and life stages need to be further developed, having a game pack dedicated to each stage is absolute overkill and I have no doubt that the majority of players would most likely get bored very quickly with the repetitious theme. Even three game packs is too much, considering we already have Parenthood.
I agree with the others that one dedicated generational expansion pack should be enough. Then, on top of that, a love and romance game pack that can include things like first crushes for kids, prom dates for teens, and speed dating, internet dating, blind dates for older age groups, celebrating anniversaries, as well as more wedding stuff and romantic dancing. With those two packs, I think we'd have a sufficient chunk of gameplay to fill the gaps we have now.