Obsidian v1.3.1 will change “open to the right” (ctrl/cmd+alt+click). Now, it will open a new tab in tab group to right. If a tag group to the right already exists, it will add the new tab to it instead of creating a new tab group.
While this is not doing what this feature request is asking, it will address the use case of users who keep an index note to the left and stack of other tabs to the right.