Well The Sims 4 finally did it.
I am finally disinterested in the series... which is an honest accomplishment.
What's wrong with it? How has it changed form sims 3.
To answer your question: Its what they REMOVED from the series. Its no longer a "life simulator." Its now a "Give us the money for stuff that players would love to have, but don't use in the first 15 minutes of game play."
Here is a review that sums up my beliefs:
https://www.youtube.com/watch?v=_BeVmHbMqAABut, i you prefer writing: Its that they've removed every bit of individuality from the game itself. Numerous people (like me) Didn't want to deal with the baby and toddler setting, preferring to goto the child life state. However, this ignores, and even disrespects the people who DID want the toddler lifestate. With the toddler lifestate, you can soak in the sims reactions as they have their first steps, as they color.
The pools would come into play LATER in the game, as a form of extravagance, to show that you have really made it. So, it took the pools away, with the intent that they would likely pay for it later, when their sims are much more established.
Not everyone would have their house on a foundation, so those were taken away.
Not everyone would create their own textures, so those were taken away so we could pay for them later.
Now, the game seems so utterly bland, because your sims are not actually yours. They're the same as everyone else. Its especially noticeable with the new mood system. Everyone is the same. There are no quirks, very little customability, and yet, we know its POSSIBLE. EA took it away, and we KNOW they are going to charge for it. Its their way, it would seem. On to of THAT, it seems like EA doesn't care. If they were to say "We screwed up, and here is how we are fixing it." They give every complaint the same response. "We listen to your complaints. We are listening, but no, we're not telling you HOW to fix it."