I feel that copyright restrictions are incompatible with a mythology in its fullest sense and function. But that doesn't stop Tolkien's work from reaching people in just that way. This creates a terrible trap for folks, I fear.
Although in a strange twisted way, if mythological traditions once upon a time were maintained by priests or organized classes of society in some way (and at times protected very fiercely) then this kind of thing feels a little bit like ... the mythology of the God of money? Whatever that might be. I don't know because it's all very strange.
Added to the confusion is the fact that copyright law is not consistent across international borders - so in particular, one poster noted fanfics being ok .... mmmaybe .... but mmaybe not. I don't feel clear on this myself. At one time their ubiquitous existence and the laws of my own region made me think they were fine but ... what if I moved or what if the laws (or their interpretation) changed? This is all in spite of the power the work has as a mythology - but these copyright laws force it to be treated otherwise. Or perhaps they force it to be treated as a mythology as mythology was once treated (in a more guarded, controlled and sanctified? sense complete with a priesthood that keeps it - I haven't decided yet on this, clearly).
In the end it all simplifies when it comes to the realm of respect and reasonable people where a simple written request to desist suffices with no need for further action or prosecution. I found this to be very refreshing, actually. No one was apparently going for blood here and people acted like reasonable adults. Nice - let's hope that continues.
Maybe they were going for money or maybe Christopher really feels some burden to act as some kind of priestly keeper of the true ways of Tolkien.
The one thing that does stand out about this Rivendell compared to any other is its religious orientation. That might be how it got "picked". I can't think of what else it could be, but then I don't know the situation.
As for creativity. We all have our influences and inspirations - including Tolkien. Imagine if he had felt the need to scrupulously strip all artifacts or influences from prior mythologies from his own works and totally generate everything from scratch as if in some kind of vacuum.