As long as the shallow base game still has more gameplay hours than most games I don't think people mind additional (also needing to be worthwhile) content costing money. That's Paradox's general business model and I think it works great for the types of games. I think I have nearly all of the optional content for Cities Skylines now but dollars per hour I'm still doing better than when it launched and when it launched the dollars per hour was still significantly lower than traditional games.

Looking at Metropolis 1998 my feedback would be I'm excited for the concept of a modern take on retro builders but I'm worried the gameplay will end up more "2D grid traffic simulator" than city builder. "Traffic simulator" can be a key layer for city builder die-hards but I'm hesitant that a 2D grid approach would be more interesting than base CS1, particularly with a free mod that simulates traffic more realistically (albeit not as performant what you can do with the traffic and road designs in 3D freeform is also much more interesting). I'll keep an eye on it though, it may be something I pick up in the future as it materializes :).