Why, after more than four years, do sims still lack distinctive personalities? (and other issues)

The reasons I bought all four bases and maybe some packs that interest me was because with each iteration I'm expecting them to behave more like humans. Humans are complex. To me, TS4 improved with human movements and movements flow more easily, however, their personalities are very one dimensional. Their emotions became a score card. How many times they were happy, sad, or angry etc. It plays like any other small game out there of how to manipulate a character to get a goal or next level about something needed to succeed. That isn't human behavior, that's keeping score.