The problem with height advantage is, as I see it, twofold. One, that it grants advantage, a +5 bonus, which is a lot. +1 or +2 would be much more fitting. Two, that lower height also grants disadvantage on attacks to you, making it effectively +5 to hit and +5 to AC. Similarly to #1, changing it to +1 or +2 would be better.
Or just removing one of the bonuses and make you either get an attack or AC bonus from height (preferably +1 or +2 instead of advantage).
I agree, and I have suggested similar changes (for both height and flanking). This kind of adjustment will be forced upon Larian once they realize their virtually guaranteed flanking advantage have royally screwed Barbarians and their staple Reckless Attack (you gain advantage on attacks, but enemy gain advantage attacking you).
Advantage may be mathematically equivalent of a flat +5 attack bonus, but with two important caveats. When dealing with high AC enemies that you can hardly hit, a +5 flat bonus is oftentimes considerably better than advantage (the highest of two rolls). Secondly, flat bonuses stack and can be combined with advantage whereas advantage does not stack (Elven Accuracy racial feat that I would love to see implemented is the closest to an exception).
