@Firesnakes, I responded to you on a different thread, but I'll repeat it here
While it is technically true that Facing rules are in the DMG, there are a other important components to that rule that Larian didn't implement. Namely, the "a creature can change its facing as a reaction to another creature's move." This component of the rule basically negates facing unless you are surrounded by enemies because you only have 1 reaction. Thus, Larian's implementation IS a rule change.
In addition, DMG Facing: "A creature can only target creatures in its front or side arc." Depending on how you equate "threatening" with "targeting", this might imply that you'd provoke an AoO from circling around a creature. Not implemented by Larian.
On all your other points I agree. Monsters can have ranges of HP, the only reason DMs don't typically do this is because it is a hassle to run encounters with differing-HP goblins. The DM is allowed to change monsters or make up new ones. These ^ follow the rules. I argue with Larian's implementation (decrease AC+increase HP+don't change Saves=nerfed ST/HP-affecting spells) but Larian is not going against the rules of 5e in these cases.
