IN ADDITION, this allows for easy creation of different difficulty levels. Story? Height for player gives +6 bonus to hit. Easy? +4. Normal? +2 Hard? no bonus
These seem like good bonuses for different difficulty levels. I would even suggest to go further and give them unconditionally to PCs. This way 15AC goblin on high ground in story mode would be hit 85% (+2 prof +3 dex + 6 story) of the time and if player really wanted, they could try to achieve advantage (98% hit) by one of the means mentioned by Isaac in the original post.