It is not about about productivity, or profit returns, or not even about the sunken cost of having a nice office that is being unused. I think it is much more visceral to the human nature.
Each person has their motivation to get out of bed in the morning. For some are their kids, for other is the dream of a better life, others are their church/community, etc. But one big invariant for most (all?) life motivations is the need to build fulfilling relations with other people: one wants to be love by others, or respected, or accepted into a group, or feared or the likes.
Rich bosses reason to wake up in the morning is no secret: it is their work. They “work” for 12 hours a day and brag about it. It is obvious they don't see it as chore like the rest of us, they can do it for days straight like a teenager boy can play videogames. To the point that it is a stereotype that these people have familiar problems and bad relationship with their kids.
But what can be so nice about work? Well, what really tickles their fancies is to boss people around. Is to have the power over them and the (oftentimes fake) love and respect of their underlings, and for the specially bad ones, their fears.
With remote work, we are crawling their drug away from them, their power, their control and their raison d'être. And that is why they are resisting and squirming, and fighting back. Don't let the addicts win.