> You can see the same "ad hoc"-ratic development "philosophy" at work in Chinese cities today.
First, it was 4000 years ago when the Chinese culture was completely different.
Other than that, it's still not entirely accurate. If anything, the planning is very diverse or bumps between extremes in China. You can check out Beijing or any historically important town with walls on the map. Most of those cities are carefully designed in square shape, and every important building is facing towards the south. Things are intentionally majestic. Form over practically sometimes.
Most of the examples you have mentioned are southern cities, which are probably heavily influenced by the Suzhou garden design. The most famous Suzhou garden is the Humble Administrator's Garden [0]. The idea of the garden is to use a lot of obstacles and irregular shapes to segment zones. In terms of practicality, it creates more "rooms" instead of wasting space with empty squares. In terms of aesthetics, it creates discoverability where every turn provides a different scene. But most importantly, it's carefully non-majestical to not offend the emperor - the holy ruler of the absolute monarchy (who can easily execute any a whole clan at will without justification). You can also feel the uneasiness even in the garden's name itself.
But indeed, a lot of Chinese cultured towns are chaotic by nature. My personal take is regions like Europe and Japan with feudal backgrounds are sufficiently decentralized with proper hierarchy, making every piece of land plan things for themselves, the lords, the church, and the guilds can design and interact back and forth. However, China is purely top-down and lacks organizations between the imperial court and individual levels (the feudal system was brutally wiped out 2000 years ago and made very few unsuccessfully comebacks). Any non-imperial organizations like mansions guides are highly discouraged as those are seen as potential threats. Chinese society in modern terms is a "flat organizational structure", and its people are just individuals (clans and families are often forced apart, and shuffled between lands). As a result, we can see towns as official projects are built in orthodox ways, which are the rest are littered with ad-hocness.
Actually, in the South, there were also quite some fortresses that were well-designed and typically resided in difficult terrains such as Tulou [1] (man, they look like Apple Park). Because they were large clans living in remote provinces, the imperial court had a hard time dealing with them so often the court didn't bother.
> In my experience, the one exception is Hong Kong
As a guy who spends most of my time living in Beijing, my first impression of Hong Kong is its chaotic (in a good way, I love it). You probably know Hong Kong is the most important reference for those cyberpunk concept artworks. Singapore, IMO, is more well thought out beforehand in terms of urban planning.
[0] https://en.wikipedia.org/wiki/Humble_Administrator%27s_Garde... [1] https://en.wikipedia.org/wiki/Fujian_tulou