At this point my hope for height advantage/disadvantage is that they make it modable.
It's interesting that you focus on that aspect when height advantage is a rules as written implementation of advantage.
Pg. 173 of the Player's Handbook:
Quote
You usually gain advantage or disadvantage through the use of special abilities, actions, or spells. Inspiration (see chapter 4) can also give a character advantage on checks related to the character's personality, ideals, or bonds. The DM can also decide that circumstances influence a roll in one direction or the other and grant advantage or impose disadvantage as a result.
Our DM, Larian, has chosen to grant advantage for positioning, per the rules.
That particular rule can be used to justify almost anything giving advantage or disadvantage - the same could be said if they'd implemented a rule that halflings get advantage all day every Tuesday. So it in no way says anything about whether a particular home brew rule is good or bad, and what a lot of people are arguing is that that particular home brew rule is a bad idea and overpowered.
Except it's not a homebrew rule. It's 100% D&D 5e Rules as Written.
Larian, our DM, is choosing to reward tactical positioning.
Although your Halfling on Tuesday suggestion is an interesting implementation of Lucky.
