I know where you're coming from. Whilst I haven't gone back to CiM1, I just haven't been drawn in by CiM2. I've bought a couple of the cheaper rolling stock DLCs, but nothing more.
And I think it's because CiM2 feels so... sterile.
It doesn't make sense, because on paper, CiM2 is light years ahead of CiM1. Fully 3D. A day-night cycle. Proper schedules. Track laying tools that are a work of art and a joy to use. And yet it just doesn't seem as balanced or engaging.
CiM1 was primitive in comparison, but so much more logical and engaging. You don't need to "learn" the way a game works when it's obvious that it would be a good idea to connect an airport, train stations and the city centre together. Yet in CiM2 we don't have any airports or railway stations. There are no sources or consumers of people, just different types of buildings that they go to to work, and then back home again. CiM1 had little market stalls that attracted people, and fairgrounds too. In comparison, CiM2 feels like an interactive 3D spreadsheet where the buildings are cells that either have a positive or negative number, and all you have to do is connect enough buildings until it adds up. Technically it wipes the floor with CiM1, but the cities lack detail and character and life, not to mention some questionable design choices regarding pathfinding and passenger logic etc.
It's such a shame, because I enjoyed CiM2 when it first came out, and wanted it to do well after CiM1 was such a pleasure. But despite the technical advancement, it doesn't have the depth.