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.
