The upper management folks also have big, comfy, quiet offices with floor-to-ceiling windows, and an assistant right outside the door to bark orders to.

The people working in cubicle-hell or open-office purgatory generally aren't the ones clamoring to get back inside the building. If offices were redesigned to give more rooms with doors to the people who want them so they can do some quiet focused work, even if it's not an assigned space, I think you'd see much more eagerness to return.