You have to think about a point you made already though. When you gave the examples for the current monsters not really having much or that so many people are already doing them that prices are going down, the same exact thing will happen with the GWD content.
GWD was literally the starting point of the reason people started hating the game. Runescape 2007 Gold. Jagex never took the time to look into balancing of the items brought in and thus kept trying to “balance” them by bringing in more stupid crap.
The biggest backers and push to bring back 07scape was for pking. 2007 (prior to GWD) was the “Golden Age” of the game before any content that changed the status quo was released. This is what the majority of people wanted, this is how the majority wants it to stay.
Prior to GWD, Runescape was mainly for skilling and pking and less so for monster hunting (other than DKs and KQ). Runescape Gold. If monster hunting is what you like to do, it’d recommend sticking to EOC/13scape where the game is now mainly for monster hunting and skilling.