The direction of D&D over the last decade and so has not been favoring more complex rules. In fact, they've been for making the game more accessible. Given the medium, I can't fault several of these changes. They're readily defensible. I think this is ultimately going to come down to whether or not the resulting rules are fun, not on some 5E purity test.
It does make a lot of sense from a simulationist standpoint to keep the height and backstab rules as they are. In tabletop there is no facing but in the game there clearly is. It's a mistake to blindly advocate for RAW when the fundamental assumptions of the game change. There is no 5 foot grid. There is no implied bobbing and weaving in some abstracted space where everyone's turns are implied to be happening concurrently.
The surface gripes seems to be more legit to me than this one. Sure they may be cool but they also make a mess, literally, of the terrain and complicate things. That criticism can be maintained in the context of the medium. I'm not sure this one can.
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.