What you describe is not the only gameplay to me, but it is indeed where the Sims 4 is lacking. Let's call it core gameplay. Due to the lack of uniqueness, all Sims are feeling the same. When TS 4 was released, I created my favourite couple from TS 2 and was ready to play with them - I couldn't. I wasn't able to nail it back then, but I'm fairly sure by now that it was because they did not show any distinct personality when I played with them.
This is as true for communication between different Sims as it is for reacting to a Sim's experience.
Things that were a viral part of why Sims formerly felt so unique are:
- interests
- attraction system
- favourites (color/food/etc)
- memories
- dislikes
- fears
- meaningful whims
- unique animations tied to all of the above - it really doesn't make a difference to have a ton of different interactions if enthuse about favourite author uses the exact same animation as enthuse about the new app your Sim just created,
and - for me first and foremost:
- the whim system being used to affect a Sim's overall feeling. I hardly ever bought something fot the aspiration points in the Sims 2, but the fact that a Sim was feeling better when he had fulfilled his whims and not fulfilled any fears - and of course the opposite - and this status being open to changes anytime was what made the game for me. That also was one reason why I never was happy with TS 3.