Well I agree with all the knowledge in the other answers, but there is one aspect of this that is totally overlooked: Pesticides. If your vegs aren’t organic grown, many of them will contain significant amounts of pesticide residues. Even more so if you dont even bother to wash them with mild soap and water before using them (but even that kind of cleaning, cannot remove them all). So to get rid of health compromising pesticides, it would be a good idea to peel. Unfortunately I am not aware how "dirty" ginger is generally speaking, when it comes to pesticides, fungicides, etc. That's actually the reason I clicked to read about this issue: maybe someone knew.
Normally I refer to http://www.ewg.org/foodnews/, when I want to update my awareness, but I can't see ginger listed there even. I happen to know that third world country imports contains many more pesticides than produce from more developed countries, and where I live the ginger usually comes from China. So my guess would be that it actually contains quite a lot of "bad stuff" on that peel. Something I wouldn’t want to eat that is.
