I was actually wondering this same thing. I personally think live wallpapers are gimmicky and a waste of battery. I thought they were the shiznit when I first got my Optimus but that feeling didn't last long
LWP are a waste just sum little goody that Google put in to make the phone look good when its on display but if i do use a livewallpaper i use the one with the grass
At first, I didn't like them, but I'm using the stock grass wallpaper now. Winter has seemed to stick around too long here (MI), and I need to see some flowing green grass, or I'm gonna friggin go nutz! LOL