For startups and other companies that might bring sales/investment prospects through it's the "developer zoo" effect and fear that looking different will turn people off. Add in marketing photos and videos using these as backdrops, now.

There also seems to be a huge resistance to giving software developers professional-tier perks or social standing, as with lawyers, doctors, and (to some extent—at least they want/think it to be so, and are insecure over the fact that it's really not) managers, even if their pay (in a handful of major markets) rivals or exceeds those.