Except Height and Backstab are exactly *the opposite* of what 5e is intended to be. Complexity through simplicity. There is no complexity when you are completely disregarding 56+ class abilities and spells.
Those do not make sense form a simulationist standpoint, at all. Because they you *must* implement hundreds and hundreds of new changes to compensate for the logic involved in those mechanics, which is literally insane. Remove the mechanics, implement a cover system, or take the 'easy' option and change them to be a static +/-2 modifier.
If you want simplification, you've already gotten it. Who is to say those other abilities will get implemented at all? From an app dev standpoint, what you say you want has already been achieved. You may not like the implementation, but that doesn't change that fact.
As a point of contention, "complexity through simplicity" makes zero logical sense. It's a self-contradictory statement. It's like asking for dry water.