I'm pretty sure David didn't intend to post on this thread - I think he meant to respond to a different thread, one in the "Admin" section of the forum regarding the old Exhibit Plus skin, which has now been updated in the skin repository (repo).
The change you're asking for is not going to be a quick fiddle. In short, the core would have to start keeping track of two different types of "hearts" on thumbnails - the ones that were applied automatically, and the ones that the user chose to apply. Otherwise, if you told it to stop automatically grabbing folder thumbnails, it wouldn't know which ones to undo, and which ones to leave alone. That would be worse than the current situation.
We've been through this before. Yet you're still not getting it. Why am I not surprised?