I completely agree with you that all Sims basically act the same, and that traits have almost no bearing on how any Sim behaves. All any trait seems to do is give the Sim various buffs, which once again don't affect their behavior in any autonomous way.
I've been playing Sims 4 exclusively lately, not because I like it more (since I like it less), but because Sims 3 no longer will play nicely on my system. I have a fairly high end system that I built myself, but it's getting older, and I can no longer afford to upgrade any of the parts in it. When I run Sims 3 with all expansions and store stuff (and since I BOUGHT it all, I'm certainly not going to only use part of it!), after about 15-30 minutes it crashes. Since it also takes about 15 minutes to load a game (once you include loading the save file itself), and about 5 minutes to save a game, the fact that the game crashes so often is abominable.
Sims 4, otoh, takes maybe a minute to load, if that. Zoning only takes seconds, and compared to the loading of an entire game for Sims 3, that's nothing; to me, that's worth the bother of no longer having open worlds. (Even though I really DO miss open worlds.) I think I've had the game crash ONCE on me in the entire time I've been playing; Sims 3 crashes every single time I have ever played it. Sims 4 also only takes seconds to save; a huge difference on Sims 3. So the game is optimized much better than Sims 3 was, that's something in their favor.
They also really improved the programming of the internal database to the game, making it so that having lots of stuff in your Sims' inventories no longer causes the game to seriously lag. (Even though it is a pita, since you absolutely cannot sort it in any manner.) Overall their programming has improved... but the loss of Sims' personalities is really a detriment to the game.
They go on about how Sims in Sims 4 have "emotions"; no they don't, they have mood swings. Call it what it is, it's no more than that. Their emotions are too easy to control, just like the moodlet buffs in Sims 3. But at least in Sims 3, if you put your Sims on free will, if they had different traits they'd actually BEHAVE differently from one another. Not so in Sims 4.
I really think that if they could ever change that - which I doubt, since I think it's core to their code - it could be a much better game than Sims 3. But it is, as I said, too core to the game, and is likely not ever going to be changed.
