I guess I’m missing “what’s missing from what’s currently available to users”?
I’ll admit that I’m a Ubuntu user so this isn’t a default out of the box Gnome configuration. Here’s a screenshot of my current desktop with the Dash to Dock shown on the left instead of at the bottom. Usually this is hidden and I only access it for Firefox (Ubuntu’s Snap version doesn’t play well with Cairo Dock) or when the Cairo Dock itself crashes at startup after certain Ubuntu updates (requiring either one reboot or a launch from Dash).
I’d love to eliminate Cairo Dock but it has a few functions that I don’t see in any of the other dock solutions like allowing you to launch a bash script that you added to the dock simply by adding the directory the script was in to the dock. You can even do the drag a file to an icon on the dock and drop it on it or pause for a moment as it brings that app to the foreground like you were showing in some of your first mockups.
So, I agree with you that a feature rich dock solution helps the user base be more productive (at least certain population of users). Yet, I think there are solutions available for those who enjoy the dock experience. It would be nice to be able to enhance the Dash to Dock with a few more features so that it could be “the dock of choice”. I’m not sure if that is something where Extensions would come in or not.