Guys @jackFang made a good point, let's please not argue about preferences in UI design. The question at hand was whether the button can be displayed again like in older versions, not whether we would like this button individually.
The answer from Carlos-Anso is on point. Even if that was a universally desired feature, it's an AOSP decision and nothing the GOS team would likely have the resources or focus to change and maintain. I think this thread can be closed (or marked solved?) as there's no change to be expected from the GOS dev team. Otherwise they can always chime in and correct me of course, I'm not speaking for the project.
vvf69107 you might want to direct your question to the AOSP devs. If they change it back, it will be back in GOS soon after.