But my preferred shortcuts for various thing would conflict horribly if everything was combined into a single mode. The number of tools in the toolbar would be annoying. The sculpt/brush settings would be fighting for space in the header against the things that used to be in the other modes. The menus would be so long.
I find modes + workspace tabs + multiple blender windows + half a dozen or more 3d viewports in various shading modes and different camera angles in each window to be quite lovely and flexible and efficient. Then you have some people who also go as far as a different scene per window and recently we recovered the ability to have a different scene per workspace tab PER WINDOW! … and you can set a mode per workspace tab.