I do miss that all other worlds were on pause in Sims 3, but I understand that they might have thought all worlds start as active seemed that could make the game seem more alive.
I personally, like the idea of a world/neighbourhood doesn't initiate until I have my Sim(s) visit it (I always turn off story progression). It makes it more smooth running for story telling/storylines. Homeless Sims/non-in world Sims/auto-generated Sims can still populate and be active though.
I'd love it if traits, likes/dislikes, etc. was reworked to stop non-immersion NPC/autonomous behaviour. Maybe even have banned activities for events (no push-ups at funerals type thing), and I'd love if we could (at least for active households) have allowed/banned activities for each household member to keep them in character.