Larian doesn't limit Facing. They expand it, making it much more easy to use. And we certainly can blame Larian for using an incomplete version of an optional rule. Just as you can defend their choice. As far as I can tell there is no DMG component of the rule that restricts it to light weapons. I will be much happier if/when this is implemented, though I'd be even happier if it was limited to the rogue and/or changed to a flat bonus.
And yes, they don't invalidate 56+ class abilities. But height/backstab (dis)advantage DO make many of these 56 abilities less useful (e.g., why Barbarian reckless attack when you can just backstab? Why faerie fire when you can just climb a ladder or backstab?). Again, replacing height/backstab (dis)advantage with numerical modifiers would completely fix these issues.
Also: Larian's fix to sleep doesn't fully correct for the HP increase. >50% HP increase for most goblins but ~30% increase in HP that Sleep affects. Sleep goes from affecting 2-5 goblins to affecting 2 at max.
Larian intends to put limit by restricting it only to light weapons per their ingame tooltip (so that's by the way to address Barbarian part, unless you do some light weapons Barbarian).
They will likely not implement "reaction" part of original rule, but they also will restrict it to to light weapons only.
Various spells being less effective is quite a big of a gap from the "invalidate" claim - after all, there might not always be a ledge and your barbarian might not be swinging them shortswords either. Sleep is arguable, because on one hand it's potentially less powerful, but on the other hand it's guaranteed effect now with set HP - you know exactly what you're getting - there is a lot of value in that in RNGfest that is D&D. They might further increase it though, which imo they could by adding another flat 6 hit points base and rank up, but that's what EA is for.
Same goes for many other spells that might be affected - they will either amend them, buff them or simply let them stay as is and the world won't end.