It seemed like the project was started with unclear/unvetted requirements, led by bureaucracy and image instead of engineering. China tends to do things the other way around.
That smoke exhaust system seems absurd - I don't know how the architectural plans even left the design phase. It should have been isolated and designed such that it could be replaced with a conventional approach cheaply.
The rest of the project sounds like a deadline-driven fixed-resource software project with incompetent management - hacks and cut corners everywhere.
Heh, funny but not that long time (started in 2006, planned to be finished by 2020), while Sagrada Familia (here in Barcelona) started at 1882 and after stopping/starting/stopping forever, it's not estimated to be finished by 2026–2028 (so about 140 years, if accurate).
tl;dr: Planned to open in 2011, it's still in construction with some say it won't open before 2020.