This is itself a really lazy and, frankly, borderline-offensive way to look at the situation. Just because a part of the setting is closer to the real world, doesn't mean that it's the 'easy option', and the fact you seem to think it is and that's why says more about your levels of creativity than anyone else's.
I think they're picking Hingashi because it's actually a really good choice for what variant dungeons can do. Don't get me wrong, I would've preferred plumbing the depths of a lost part of the Shroud too, but a strength of variant dungeons is that it's a piece of content that can tell multiple different stories in the same place, fleshing out a part of the world more than a single focused dungeon. Sil'dih used that quite well to deepen parts of the Thanalan's story that were only vaguely implied and show that Ul'dah isn't just any one part of its past, and Mount Rokkon could use the same to get a lot of even worldbuilding out of an area that has very little, while just, say, a Hingashi regular dungeon risks defining inner Hingashi purely as one thing.
...of course, all that is assuming Mount Rokkon is in fact Hingan. I'm conscious that we don't actually know that for sure, we've just been assuming that because it's a more interesting option than Doma.
