Re: I think we're reaching a point...
One large building might make for a more focused target, but it's not obvious that many scattered targets, with a larger attack surface, a wide range of access devices in use, many personal and not under meaningful central control, and with varying local arrangements for digital and physical access, would be either more secure, or as easy to secure.
I wonder how many people work in the local Starbucks, etc., without a thought of Wi-Fi security / snooping / infiltration / etc.
Not that remote working doesn't have many advantages, but it also has weaknesses and security might be one of them.