It not only makes the figures too tall, it also means there's a lot more math involved with creating scenes, because approximately 103.2 inches is a totally non-intuitive scale. For example, a 6' figure becomes .697 PNUs, while a 5' 6" person is .639.

If the reason for using PNUs is gravity, that's adjustable. It's a lot easier to pick a scale that works, and calculate what the value for gravity should be. Once you do that, you can use the same figure every time as long as the scale is the same.