In my opinion, the sidebar in the new theme is helpful but underused.
The sidebar could be helpful, but it has too few useful links, which makes it a waste of space. One possible use of all of this space is in going from a meta site to the parent site. Currently, the easiest way to get from a meta site to the parent site is by using the menu on the top right.
For me, that means moving the mouse over to the button, pressing it, waiting for the menu to pop up, and having to scan over the communities to get to the current community. As soon as my eyes have moved there, the sites list loads, making me involuntarily look down to see what the motion is. Then I have to remember exactly what I was doing, look back at the communities list, move the mouse over to the parent site and click it.
I know this isn't a major inconvenience, but I think that the side menu could speed up this process.
Messing around with the Inspect tool, I created these two screenshots of what the sidebar might look like with the new link. Keep in mind that I am neither a professional developer nor a UX expert, so the link could be moved below the home link and/or change to look like the links below.
In my opinion, this would make the sidebar more useful and speed up switching between the parent and meta sites. Does this make the site easier to use, and if so, is it possible to add to the new theme?