For me, it's how hard it was to edit townie's appearance. In the previous games, you either needed expansion packs (TS2 Open for Business or TS3 Ambitions) or cheats (boolprop testingcheatsenabled true). In The Sims 4, you can just do it through Manage Households through Manage Worlds easily without careers or businesses.
Oh, and in the previous games, you had to use a mirror to change hairstyle, makeup etc and a dresser to change the outfit. It wasn't that bad in The Sims 2 for one reason: when you wanted to make a hairstyle different for each outfit, you just had a handy button for it in the hairstyle chooser. The Sims 3 was way worse. You had to use mirror to change hairstyle and make-up, then exit CAS to change outfit, reenter CAS to change the hairstyle and make-up for that and repeat until all the outfits are done. There was only one way to bypass it: the Stylist Station, but it took a lot of room and came from The Sims 3 Ambitions (not to mention that this won't help with toddlers).
Oh, and you could only add more outfits in one category in The Sims 3 through Change Outfit or Stylist Station.
And don't get me on how the outfits in The Sims 1 worked. You can change the everyday outfit at any time through a dresser, but to change the other outfits, you needed to go shopping (which required expansion packs). Plus you could never change the face.
And some other features I found annoying from the previous games:
- That cow mascot from The Sims 2 University. They even ruin your romantic relationships!
- In The Sims 3, taxis in the future were slower than taxis in the present.
- How I played The Sims 3 muted because at any rare moment a meteor could fall (Ambitions).
- Stuck in one world in The Sims 3. You could move worlds, but all those previous things will be gone forever. Move back there and it will be like it used to be at the start. I have to make my own worlds so the world has all the expansion pack features!
- In The Sims 2, let your pet chew/scratch your furniture long enough and it will be gone. The replace feature is a really convenient feature! Just it would be great to have it for stolen stuff (otherwise I can't stand kleptomaniacs in The Sims 4)...
- How difficult playing rotationally was in The Sims 3 without mods.
- How presents could actually be rejected from time to time. Yay! What do I do with that thing now?
- How roaches made sims cry in The Sims 2.
- The Sims 1 dragons that set things on fire. After all, in The Sims 1, once your sim catches on fire there, they are dead for sure.
- In The Sims 3, when a NPC sim dies, their new gravestone just disappears. If they were friends, you could find their grave in the mausoleum, but otherwise they'd be gone forever. What if I wanted to put it somewhere in the graveyard?
- How needs in The Sims 1 left a dire consequences in breaking the strict routine you had going on.
