Attention to detail. All those little moments where Maxis added little quirks to the Sims, or chances for them to do something unexpected. The Sims 4 is too straightforward--you get your Sim to do something, and you'll get exactly what you expect, with no deviation, leading to all Sims feeling the same.
Aspiration failure.
The chance of failure in general. Sims 2 is a GAME first, not a screenshot generator.
Cars. They've got the same closed-off worlds that Sims 4 has, but they still have cars. It's doable. And by the way, those were the best cars in the series. Sims would actually animate getting into them, instead of Sims 3's method of teleporting inside.
Burglars.
Premades with lore that actually matters and is reflected in-game, because they start with actual stories that you can play through. You could ignore that and do your own thing just like you can now, but you were given the OPTION to play through a guided story before entering sandbox mode. Daniel Pleasant cheating on Mary-Sue. Don leaving Cassandra at the altar. You started the game right on the precipice of these events, and were ever-so-slightly nudged in that direction.
Community lots that offered activities OTHER than drinking.
Cross-pack content.
Attraction. Seriously, it's the most obvious use of Likes and Dislikes, and something that modders added in on like day ONE. What's EA's excuse?
