I just created my first TOC in a panel in XWiki. I like this because it gives me a good overview of what exactly is on the page and where. I combined it with making the panel sticky so going through the different subjects on the page works really zippy.
I want to be absolutely forthright with you fellows, just so you know where I am coming from. See my experience as a fresh user input. My motto here: Honesty saves everyone a lot of time.
The thing that was challenging at first was: How do I create my own panel? I know I already did such a thing but that was a long time ago and I simply forgot how. So I looked around on the Global Admin Panels page but I could not find any word about “creating a panel.” After a quick internet search I saw that there was simply a page called ‘Panels’ and I could do my business there. A bit frustrated (and mumbling to myself why I could not find any reference to creating a panel) I searched for any reference to this page on the Global Admin Panels page and ultimately there it was, a link beside the bottom buttoms that said “Go to Panels.”
Having found how to create a new panel, I immediately created one and with some advice I found on this forum (Table of Contents in a Right Panel) I had my TOC panel ready to go. So I went to the page I wanted to add the TOC panel to and then I was stopped again because I did not know what the reference to the panel should be. So I went back to the panel I created but there was no reference to the name I had to use to include it. A few tries later (first on the name, later on the name in lowercase) I remembered that the former panels (which I already handily deleted) were in the form of a short XWiki reference. So I tried the reference “Panels.TOC” and there it was.
Sorry for the long story (which is a bit off-topic) but I wanted to make a point here. We (you) are discussing the automatic generation of a TOC and one of the best proposals IMO is the addition through Panels. I think it gives a lot of control. The auto generation is a nice and shiny feature but an admin can make XWiki nice and shiny. That is one of the main reasons I use XWiki, it is so hugely versatile and customizable, for me it’s hard not to love it. But this is the point here, I think one of the biggest ‘selling points’ of XWiki is it’s customizability, it’s depth and versatility (and way more than that). Besides that, it’s Java based instead of (the perhaps soon to be buried?) PHP. But here I am, bumbling my way through the versatility of XWiki (which IMO should totally not be neccessary) and we (you) are talking about adding something nice and shiny.
But to get back on topic 
- No thank you, I make it shiny myself and if neccessary will add my own short info page on how to add a TOC (and footnotes, links, images etc. etc.) for the users.
- No, same as above.
- No, I think it is more wise to keep the tree node for pages/spaces only.
- Yes, why not? I fully agree with @CharpentierLucas on this.
- No, the reason: “Stop driving my car”
This is a display/design feature which I can easily add myself if I wanted to.
To be short, XWiki is so customizable, everything is possible. But the ‘directions’ on some important functionalities have room for improvement. Just some text and a link I think is not too much to ask for.
PS
Oh, and why the popup info on the Global Admin Panels page (Panel List tab) on the text at the top? Why not just plain text added to the text already there? Just asking.