Swimming helped build athletics, you could lounge in the water, and splash people. And yeah, the worlds were shells, but that's more acceptable in the Sims 3 because of the variety of lots and ability to customize the world much more. You could make a town more immersive and fun to play, and it helped craft a unique aesthetic and feel. I loved making Sunset Valley a creepy goth town.
I agree that the bar is low though, and that the Sims 3 worlds aren't perfect. The open world mechanic had its flaws, which is why I'm fine with the closed worlds of Sims 4. I just feel that Sims 4 worlds really should have more going for them. The worlds are a big selling point now, we can't make our own worlds, and they've already shown with some of their packs that they can make them more engaging.
EDIT: Done editing. Sorry about that, my English reading comprehension has gone to poop.
