- The pre-commit issue - In the western world (not always the same in China, Dubai, etc.) most developers work on a debt finance model where they have to sell a certain percentage of apartments or pre-lease a certain amount of office space before the finances come together to develop a tall building. The taller you go the tougher it gets.
- Market reactions to complex ownership structures. Owners for office buildings are still typically single institutions. Owners for residential buildings are typically individuals with some kind of shared structure for payment of common building issues. When you get a tall building that contains offices, hotels, residential, retail, etc. it all becomes complex to manage and many potential investors/owners/purchasers have a major feat of this that drive them to simpler mostly single-use structures.
- Airspace limitations for aircraft manouvring. Though the enforcement of these varies by country - some are strong on it, others ignore them (Taipei 101 in Taiwan is one that is very close to flightpaths). Helicopters to urban hospitals can also be a big thing.