I disagree. Media Center is not an appliance which comes with a paper manual.
It's a piece of software, and software should be able to explain itself clearly without having to reference external materials.
The devs have stated on many an occasion that there is no manual other than the Wiki and Interact. Many Wiki items are simply links to Interact, which is better than nothing and often enough to get by.
Disagree with your comment about reference to external resources. Linking to external references for help has become a software norm. Main stay products like Word and Excel actually eject you out onto the internet when the F1 help key is pressed.
... it's difficult to keep a wiki up to date, and unless you are employing someone whose job it is to keep the wiki up to date, then it's taking time away from further MC development.
Improvement of the Wiki and making it current could be tied together with your previous comment?
I had hoped that it would be MC20, but I'd love to see a release which is not focused on adding new features, but rather focusing on ironing out all the little bugs and inconsistencies in the program. Revamping the UI and making the program easier to use - while trying to avoid making it difficult for existing users to upgrade.
I see UI improvements and explanation of how they work are aimed at the same target but they just work at different levels of detail.
I think your sentiment of winding back on new features makes a lot of sense. As with most things in life it's about getting the balance right and that balance is subjective, depending on your outlook.