The Sims 4 fixes so many problems that were in 3. The open world in 3 was too ambitious, and slowed things down WAY too much (not to mention causing countless errors by trying to do too much at once). Having multiple smaller areas within worlds allows the FEEL of an open world without the insane performance hits.
And to be honest, I’m not missing cast at all. It slowed my (normally peppy) PC to a long stutter and was just too tedious and time consuming.