I'm planning on making use of the sidebar on nearly every page of my site, and looking at it, there are more template edits than would be required if it was done a bit differently.
The first change would be adding settings for displaying the sidebar (either site-wide, or on page-by-page basis). Could also include an option for removing the visitor block (with page-by-page options).
The second would be adding a sidebar template, using conditionals to display the sidebar on the pages selected in the options.
The third change would be adding a sidebar_xxx (example: sidebar_forum_list) template for pages, so that changes to the sidebar can be done on a per page basis.
I'll probably look into making this an add-on, but I think it should be added to the core, if at all possible.