Carl's take of ways for improvement.

Carl is right about the game growing linearly but not getting any modification to game play. If you look at the wiki page for each trait in the Sims 3, you'll see a pretty long list of ways the trait modifies the original game play. This is in addition to, or in modification of a pretty decent and in depth game with lots to do. Some traits had as few as 5 changes, and some as high as 18. I did not look at them all. And these lists are only direct changes. They do not list how all traits stack, interact, modify each other, or effect skills, such as being able to paint a unique style of painting, or succeed in a particular genre of writing. This is additional. On top of that, if you average something like a dozen changes PER trait, your sims can have 5-7 traits! If you multiply that, that's a lot of changes! Both for your play style, benefits and downsides in the environment, social interaction, and career. All the sims in the world have that many differences by the traits they have, too, and there are a lot of traits! In addition, there are changes based on skills, on career, on your degree, in 3 social groups, celebrity, and many life states, which again combine with the huge number of unique factors for EACH trait, let alone 5-7 of them. Put that into an open world with many sims with 5 traits each, and all the other factors like life state and social group, and it's fantastic. It's complex and interesting. It has depth. It's immersive, funny, fun to play, and highly replayable. All these factors knocking heads in the open world lead to fun games again and again. The Sims 4 does none of this. I simply did the same boring things again and again to get in the mood for work, and social interactions were very boring. That immersive, in depth glow I expected from the Sims was totally missing. What the Sims 3 lacked in complexity in actual game play (we all know how to eat and go to the bathroom) it more than made up for in the complexity of the game itself - the nuts and bolts behind those traits, life states, and social groups was complex enough to make a game where you click to do basic life functions again an again a joy to play. The ability to truly customize your create a sim and building experience, to quite a degree of difficulty if you wanted to, always added depth where it was needed. The Sims 4 doesn't really have this. There isn't the depth to traits there was before. The emotional states are shallow and few. There is no way to customize objects or clothing. Social interactions are boring to do and watch, in a small world where nothing unfolds out of that chaos of so many traits and states with so many factors that the Sims 3 has.

It's hard to explain that particular joy you feel when something truly hilarious, clever, and true to life comes out of all those traits and factors bumping into each other in that open world. The lady in the pink pick up truck. The day Tom Wordy showed up to the party a werewolf. The day the Murphy Bed killed Tiberius before classes even started. Scouring Bridgeport for the perfect date only to find out they're a burglar. The way the butler kept quitting until I got a damn cat. Playing for tips and being everybody's best friend without knowing a thing about them. Putting a stereo out for the zombies. Being so hungry you eat spoiled pumpkin pie. Getting pranked or scared in public and peeing yourself so your reputation goes down the drain. When the drummer cheats with the keyboard player, or your horse eats your newspaper and digs up an onion while stamping to the stereo, and your klepto spouse comes home from work with a street light in their inventory (I wish I'd waited to learn that last trait before putting a ring on it, but I'm not going to change you.)

That clumsy, loser, hot-headed, socially awkward, inappropriate mayor really has a different effect on the game from the charismatic, family oriented, good, workaholic, ambitious mayor. It's an open world, with many differences applied through each trait, life state, job, and social group. In the background is a wonderful chaos that yields some really fun results. The words that came to mind when I played The Sims 4 were vapid, void, and shallow. There really isn't the depth of intricacy to the traits and how things work to give the in depth feeling the Sims 3 had.