Surprisingly, there was a report a few years ago that the distributed nature of Airbus also was more efficient. But yeah, it's mainly for political reasons.
There hasn't been a professional sports stadium built, ever, without an "independent report" that said building a large concrete mausoleum employing mostly minimum wage workers for only part of the year, and with rich employees and owners that spirit most of their earnings out of state, wasn't the greatest economic benefit ever for their city.