[Pedestrian]

^^Very tall towers only make economic sense where land is scarce and expensive and I agree with Steely that economic factors are controlling in these cities. But none of them really have the kind of land scarcity and cost that justifies building very tall.

In undemocratic countries (and even some democratic ones), trophy buildings get built as vanity projects. Less commonly, a private company will do something similar (and the record is full of companies that found themselves in economic difficulties soon after building vanity headquarters buildings--consider such as the Sears Tower and Pan Am Building). So I'd suggest people look for a city with a corporate headquarters of a company so successful it has the ego and cash to build (or lease enough of to put its name on) a vanity HQ in these difficult times.