I am considering to remove all 'subgenre' functionality from my 'enhanced genre hierarchy list'.
The reason is that by now I believe that while the idea makes sense, in reality it is difficult to put to good use.
Firstly, there is no genre provider that offers structured genre/subgenres that can be retrieved and automatically tagged. So it will take a lot of manual effort to set things up and maintain them.
Secondly, while some genres can be clearly considered to be a subgenre of another, many others are not a subgenre of one genre, but evolved from two different genres. Sometimes genres that are not even in the same 'category'.
It's pretty much impossible to define/restrict these as being a subgenre of one genre.
Also, because of the way the hierarchy browser works (my THL at least), having subgenres doesn't really add any functionality to it.
Using the hierarchy browser will find them irrespective if the genre resides in the 'genre', or in the 'subgenre' tag.
So these days I myself put all genres and 'subgenres' in the genre tag.
If I remove the concept of subgenres from my list, it does not mean that any genre names get removed, nor that there will be any change in the hierarchy. (levels)
It would only mean that it won't read the 'subgenre' tag any more, nor will it provide suggestions to write it.
If anyone using my Enhanced Genre Hierarchy list does use and appreciate the subgenre feature, let me know. Then I will leave things as they are.