I don't care for activities sold separately. Being sold separately doesn't mean that they'd have any more depth or fun inherently baked in. They don't.
Just look at the bowling SP. The Sims don't talk to each other while bowling. No high-fives, no trash-talking, no teams, no picking up spares, no genuine scoring based on the pins we saw knocked down, nothing that makes bowling fun. It would have been nice to even have one Sim designated as a scorer. Put them to sit at a table with a pen and paper and react to the ongoing game. Not even that. Nothing.
So, if this is what piecemeal activities are going to be like, no thanks.
