The funny story about it is that Japanese were unpleasantly shocked with architectural, and engineering plan "sounding scarily too realistic," and asked to "dumb it down a bit," for what the architect refused, and thus it went to Martin Pascoe.
I guess they were afraid of Tokyo actually asking them to go forward with it.
To summarize: they're very expensive to build and the turnover is uncertain.
[1] Why Dubai Creek Tower Stopped - https://www.youtube.com/watch?v=IPUOOz30dJQ
[2] The Greatest Skyscrapers Never Built - https://www.youtube.com/watch?v=7RxbSBWC8hw
[3] Will There Ever Be Another World's Tallest Building? - https://www.youtube.com/watch?v=T4CCY9RJeD4