You are equating the removal of a bonus for ranged attack from high ground, with removing combat tactics. You have nothing to support your opinion, other than "you believe that high ground should give "some bonus", while completely ignoring the inherent benefit of getting to high ground, less chance of a ranged character being pulled into melee, and greater chance of maintaining concentration spells.
Getting to high ground does not make a person more accurate with a ranged weapon.
How does high ground help maintain concentration?
Indirectly, of course. If people on low ground have disadvantage to attack = less chance to hit = more chance to maintain concentration.
