I wasn’t aware of this feature request already and I made a similar request here:
I agree that using the index page is better than the current landing page.
One item that I have seen in other documentation platform that is currently missing from Discourse documentation is the previous and next buttons that automatically shows up based on the previous/next page in the index. That helps the reader to walk through the topics in the expected order without the need to go back to the contents/index page or use the sidebar. Here is an example: