Kasper brought a good point up there.
The problem with 110 floor buildings is that if an aircraft hits say the 90th-100th floors, it'll take firemen at the least 15 minutes to reach the top, by which time they'll be exhausted. And also, how are you going to put a blaze out 100 floors up? Difficult, if you ask me. Added to this, by the time the fireman have fought their way past all the people escaping the burning inferno, the building would have collapsed, which is exactly what happened on 9/11.
Architecture is going to take on a far more different angle from now on. Pity though, because I love skyscrapers!