While I agree that a lot of it is unregulated re-labeling, without the kind of care for cross-contamination that would be truly useful to the food-sensitive, I would imagine that it has net improved access to allergy-reduced/free foods. I like to think of it as fad-eaters subsidizing the dietary options of those with true diet restrictions.

And, I believe FDA issued regulatory guidance on the definition of "gluten-free" not that long ago:

http://www.fda.gov/food/guidancereg...atoryinformation/allergens/ucm362510.htm

...pronounced like the long vowel and first letter of the alphabet...