I have been working remotely for a US corporation (sector-specific hardware and software) for over a year. Although they have a physical office, and I also live in the US, there have been no mentions of visiting the office or any other get-togethers.

Perhaps, as other people mentioned, having many developers working from overseas, as well as key developers working remotely, disincentivizes the company/department/team from trying to bring them together in-person.