The original left column idea came because we wanted to add properties syncing. But some types (mesh, curve, surface, armatures) already toggled edit/pose mode when clicking the data. So we decided it was best to preserve the current behavior for toggling modes, but also add syncing.
I’ve discussed things a bit with William and Brecht about this Left/Mode column. We decided that cameras and scenes should not be in the mode column. We may potentially remove collections as well, in favor of the current 2.83 behavior of selecting the collection. The mode toggling will stay for now. I’ve already removed cameras and scenes from the column in my branch. I haven’t given up here, but I’m putting it aside as it works well enough for now (just needs polishing). I would like to get continued feedback here and get more input from the UI team.
So now I have started working on properties sync/selection! I would love to hear what you all think! It only works for a few types (world, camera, mesh, curves, materials), and I’ll add the remainder soon.
Could you be a little more clear? I think there is great visible differences (names, icons, colors) between types of objects. Also, thanks for sharing that you don’t like the left column, the criticism is good 
What do you think now that it is focused on mode switching?