To me, 5e is a ruleset that is pretty well balanced, it does account for things like surfaces, so i dont think it's wrong for Larian to include them, albeit I think they're far too free with them right now, and the D&D approach to a surface would be an area that 1) probably counts as difficult terrain and 2) would require a save for no damage or half damage, only taking full damage on a failed save.
IMO Larian has a decent enough basis, but changes way too many rules, whilst I get that some rules will absolutely need to change to work for a CRPG, I don't think lots of the ones that have changed had any reason to. stuff like changing what type of actions things are, messing with jump distances, merging jump and disengage, double bonus actions on rogues, everyone being able to use scrolls, messing with spell effects, wizards being able to learn any kind of spell etc.
It's still a good base, but ultimately disappointing right now, at least for me.
