Could make more sense when connecting already public spaces. Let's say vertically built shopping malls directly connected to some big metro/train station. From there you could reach your premium office spaces farther away from the station. There must be some sort of gateway/junction point which would be public but other than that office space could remain off limits. I doubt you'd have random people walking through your cubicle.

To connect a grid of buildings, multiple skyways. So there must be a 'freeway' through each building, for traffic passing through. Using up valuable floor space, chopping the floor into pieces, noise outside your office. Not good however you do it.

We have these in downtown Cedar Rapids. Its awful.

Matter of taste, I believe... For me this public floor wouldn't be a waste. You could have boutiques, newspapers stand, florist or cafe, you name it, similarly to ground floors. When you have 50 floors "wasting" one or two for the connection shouldn't be a big deal. Of course everything boils down to how well is it designed and implemented and how many people actually uses it. In my place there are skyways between big department stores. Only two and not that spectacular but it works nice, is convenient, doesn't spoil overall architecture. I'd gladly see more such solutions in future.

Hah, interesting. I'll make a detour through Cedar Rapids next time I'm in the area to check them out - the disadvantages are far from obvious.

Further you need a map to figure out where to go next. The locals all know, but to the uninitiated its a maze. So you get confused folks wandering into the wrong places all the time.