Sims 2 has so many things, like Sims 4 is nice to play, because you can have more options in CAS, like skin tones, being able to make pets, etc. it does really look pretty, and I do enjoy the game packs I got for it, but I went for packs I loved in Sims 2, and a few packs that Sims 4 offered.
Now, back to the question, Sims 2 does almost everything better than Sims 4 in a lot if ways. For one, their were wants and fears that actually make since, where whims seem more empty. In Sims 2, you could have a Sims with almost the exact same astrology sign, and a few others, but feel more real because they won't be 100% the same.
Also, teens look like teens, and not adults, where you can't tell the difference between the two. Plus, the gameplay in Sims 2 threw some curve balls at the player, where the results could change the outcome of the game play. Plus, Sims could be killed by flukes, like looking at the sky too long and get killed by a satellite dish. You can more or else control the Sims however you wanted, but the game play could switch things up.
Sims 4 doesn't really offer much random game play, and most of the stuff that makes the game fun in Sims 4, gets nuked, because people complained about the feature. Like, don't but Vampires, if you don't want to deal with Vampires.