Perfectly understandable. I wasn't trying to make it out to be a 'must have!!' thing, merely that there would be possibilities that could be utilized with it, as I mentioned, for newer areas and regions. I wasn't implying 'hey, let's build Ravenloft from scratch all over again', but moreso something along the lines of 'this could be an extension of the swamplands' or possibly a future basis for Mordent. Mordent seems like the place to focus more on gloom and damp terrain, and there's a lot of ghost stories with things like haunted mansions and such - things that would benefit from a tileset like the Fantasy Interior one.
To be perfectly fair, if it's a question of confused aesthetics, for the most part it's a question of lighting. The inn, castle and dungeon portions in Fantasy Interior are, for example, very similar to the Barrows, City Interior 2 and Fort Interior tilesets, simply with a few new features like cracks in the walls to 'crawl through', higher ceilings (perfect for areas that might be more intimidating) and big holes in the ground where water leaks through, and a few other features that elude my memory at the time. With the exception of these features, they look very similar to those aforementioned tilesets that Ravenloft already uses for areas like Krofberg and Blaustein.
Again, if I'm coming across as pushy then I should apologize in advance. I get carried away when I see something that has potential for use, and my mind already starts coming up with locations and ideas for how to implement those things, and so I get enthusiastic and all "Hey, this would go great for this! And this could go here!". So yeah, this is still just a suggestion and me more or less attempting to rationalize with your, perfectly valid might I add, reasons for why you might be unlikely to implement the tilesets.