My favourite English HeroQuest (1989) expansion is the classic Adventure Design Kit (1990), as it gave us the ability to create our own content for HQ without having to use a photocopier, scissors, & glue.
The ADK consisted of a booklet, blank maps, bigger character sheets, & stickers of the quest icons.
This was not the first time we were told to make our own content however it was the expanded version of what was presented to us in the 1st printing of English HeroQuest (1989).
Suffice to say making HQ into whatever suits you has always been part of HQ, & every official quest release by MB Games, & Avalon Hill demonstrate that the only limit to the Game System is your creativity.
That's a point that needs to be made, HQ is not just a board game, it's a board game that operates on a Game System, & that system allows infinite tweaking, modification, & transformation.
That's why HCHQ exists, it's part of the official HQ system, the same way all House Rules are.
As for the products, all Hasbro (the owners of MB Games, & Avalon Hill) wants from us is our money, so as long as we are paying for their products, they don't care what we do with them.
So prepare for some more mature High Adventure in a World of Magic in video format on YouTube... eventually.