It all points back to every luxury brand, regardless of origin, wanting to seem European, especially like German upscale brands. What the non-Euro brands rarely understood, or eventually forget, is that there is (or was) logic and meaning in the Deutsche-luxo name soup: it told you something about the car itself, usually something about size class and/or powertrain.
Some of the invented Japanese luxury brands got this, and mostly still do. Cadillac and Lincoln just need to stop trying to be non-American with their nonsense model names (MKZ? CTS4? WTF).
These Hyundai model names have no meaning because they're pure marketing constructs. Beyond "G is for Genesis" and a vague notion that 90 is somehow more than 80, they're empty.