To me it felt more like a blend of new features, missing features and parts of the game that just work differently now.

I didn’t even get deeply into some of the mechanics on my first run (parking, for instace) and more complexity isn’t always better, so I often spent more time on these on vanilla, but if they make a beefy expansion and keep fixing bugs it may prompt me to return and see how much the balance of my old city and the process of making a new one are impacted.