About the Specialisation Index ...
For those who haven't seen the feature yet: the specialisation index (currently being tested) locks certain buildings away until you've reached a higher score in that specialisation. Reaching a higher score is done by putting more buildings in that specialisation together.
My first question: why? Why do we need another complication?
Secondly, why punish players for designing their cities the way they want? Isn't that supposed to be the idea of the game?
Thirdly, for some specialisations it makes zero sense to promote placing more of them together. A monument is supposed to be something unique, something that dominates its surroundings. Who's going to place the Eiffel Tower next to the Pyramids of Gizeh? Why would I want Himeji Castle to be standing next to the Lines of Nazca?
Likewise, why would I need to put three or four transport buildings in close proximity? The idea of a transport building is that it links a certain area to another area, usually farther away. The goal isn't to link the transport buildings themselves.
One more example: if I place a big arena from the Entertainment specialisation somewhere, I'm not going to put another one next to it or soon an entire part of my city will just be arena's.
For some specialisations, like Education, it may make sense to promote clustering. There are probably many players who like the idea of building a campus, dedicating a bigger part of their city to education buildings.
But for most specialisations I'd argue that there's zero sense in expecting many of them to be placed together. Sometimes I'm scratching my head and wondering whether you guys understand the concept of a city (like when a train station only has a service area that stretches to two or three residential zones or when two parks can't be placed together and each must be connected to a road, because no one apparently was ever able to walk from one park to another one bordering it).
Anyway. To conclude: If this feature is going to be released like this, I absolutely don't see the benefit of having it. It's non-sensical in most cases and it severely limits players' freedom to just design things the way they want to design them.