Is there a way to keep the left hand side menu expanded?

If you fix the menu to be always visible (refer to CSS above), I think that will largely solve your problem. It will effectively revert to how it was before the change.

The reason we’re collapsing the menu is to make way for future mobile enhancements (as mentioned in the original thread). These changes are difficult to implement with that menu where it is, that and the issue of duplication.

Even with the menu collapsed, most areas should be just one click away or accessible using the keyboard shortcuts.