
It just breaks the cell walls, is all, doesn't "destroy" anything else - if you plan to grate it before serving, then cell walls aren't necessary. I often use frozen ginger in Indian dishes where it's grated then fried, and don't notice a difference in the flavor. Ginger tends to sit a long, long time between orders in our local grocery, so I like to buy a lot when it's fresh and freeze it.
Reason I ask, is it's a
long drive to the Asian market in the "big city"

and they don't always have fresh wasabi when I go there. I might be able to get it once or twice a year tops. Eden Foods has powdered dried real wasabi, but obviously fresh is way better.