I mostly just changed them because the old ones weren't very useful in real matches and were more just references (I do see your point though and I understand what you mean). The old nair was kinda redundant with other moves and bair was really jank sometimes.

If I ever get to making abyss rune support for the abyss rune buddy I'll probably try to add a rune that brings them back when enabled, though runes make balance patches a little annoying so I'm not sure when that would be.

Honestly you could always replace the bair with a move that's both good and a roblox reference. The nair being very generic works fine, because it's a nair, it doesn't have to be a reference, although you could make it both a reference and a good move at the same time as well.
It's not impossible to have the best of both worlds if you get creative.. though, coming up with new stuff like that can be tough sometimes, so I wouldn't blame you for not doing it.