I'm not sure Phoenix will ever get a building that tall. Where would they put it? The airport height limits downtown (the most logical place for a 75-story building) pretty much guarantee that nothing taller than about 600 feet will be built downtown. You have to move north of Roosevelt to escape those height limits and as you move farther north, away from downtown, you get closer to the adjacent residential neighborhoods on either side of Central Avenue who urinate and moan over just about any project taller than 300 feet, like the end of western civilization as we know it is imminent if the city approves the project. You get into a clusterfrack of NIMBYs and BANANAs who go bat-poop insane over anything more than 25 stories, with choice comments like this (culled from prior city council or village planning meetings I've attended over the years):
"It will make Phoenix hotter, with all of that sunshine reflecting off of the glass." Really, how do you come by these gems of wisdom? You have scientific studies to prove this result or are you just pulling this stuff out of your Depends-covered arse?
"It will make traffic worse." Um, you think? Usually building any sort of high-rise that increases a city's density will increase traffic to some degree, but so does adding another single-family home sprawlburb subdivision in Timbuktu. I guess some people think Phoenix should be a static city, never-changing, for all eternity.
"It will depress our property values." Wow! That's amazing! Funny how overall market conditions (that might depress values right now) or the fact you live in a close-in neighborhood (that might pump up close-in property values) has nothing to do with that.
Others have touched on the other reasons for Phoenix's lack of height: Lack of corporate headquarters, lack of economic activity justifying the need for supertall buildings, etc. ad nauseum.
--don