Yes, DE is a waste of money. It doesn't control lice or parasites, and it's bad for chickens to breathe the dust.
Since raising chickens, I have changed my mind about the merits of going completely organic. Organic "remedies" like diatomaceous earth or fragrant herbs are at best ineffective half-measures. I still feed myself and my birds organic grain and produce, but if my birds (or I!) have trouble with fleas, lice, mites, or other parasites, I use modern medicine to cure them (or myself!)
I no longer buy organic meat in the grocery store, either. I used to insist that all my meat be raised completely organically, but I now believe that it's cruel to raise animals or birds to suffer with parasites or other ailments that can quickly be addressed with permethrin, ivermectin, or amprolium.
After all, I wouldn't let myself, my family, or my pets suffer when an effective remedy is available -- why should I require that my birds or my meat suffer?
Nope, no more organic meat for me. "Grass fed", "hormone free", "cage free", and "free range", YES; but "organic"? NO.