The sims 4 is strongly a sandbox game, although it does have a weak life simulation. I believe the game is lacking the structure seen in previous titles. I believe the series is best when balanced; that is what made the series successful.
Sims 4 went too easy, whereas sims 2 and 3 (cannot speak for sims 1, never played) adds elements of surprise and chaos which we need to respond to. I find that each game of Sims 4 has become the same scenario and there is weak diversity in sims (that is - in terms of traits and behaviors). An example of chaos is the burglar; it is well balanced because it adds an element of chaos while it is not devastating nor causes irreversible damage. I also miss the special little touches especially seen in sims 2. @phantasmkiss You mentioned the child standing on dad's feet. Sims 2 is filled with so many hidden gems such as subtle behaviors seen depending on the situation. I remember there being 2 youtube videos a little while ago in which someone found a large list of hidden sims 2 gems.
Of course, we don't want to swing too far in the other direction either, because the series has always allowed its followers to be creative and do story telling.