MonsterEnvy
Legend
I just find the whole demi-plane thing weak and distracting. I think it was introduced as a blunt solution for the fact that Ravenloft world seems more Georgian/Victorian hinterland or Late-Renaissance era than medieval.
How is it distracting. While moving around people find mists. When they enter it they end up in Barovia and can't leave. It was done this way so that Ravenloft could be put anywhere and take people from anywhere
If they do find a way out the Mists and Barovia are gone. No evidence exists of it other then that the mists may reappear somewhere else one day. Anyway the fact that it is a Demiplane separate from any setting is a plot point in the book and allows for cool cameos and other details. [sblock]Mordenkainen himself shows up there and if you just put in the realms somewhere then he can't do that[/sblock] Overall I find putting it in the realms somewhere weakens it a lot more. As it means that anyone in it are just people from the area you put it in that wandered in and limits the diverse number of people that come into the land from different worlds. Plus it ruins the plot point of the mists showing up anywhere to bring people to Barovia. If all of it is bound to the same region.
Also Ravenloft is very medieval, not at all victorian or renaissance like. I am guessing you don't know much about Ravenloft or Barovia.