Gluten is extremely healthy. The few actual celiacs I've met would have certainly liked to be able to eat another cheap, healthy source of non-animal protein.
Soy allergies according to CDC are about 1.2% of general population. This makes it about twice as common as celiac disease (from NIH numbers) https://www.ncbi.nlm.nih.gov/pubmed/22850429
Where are you getting that 1.2% number? This is the only study I've found citing that number, but it is _not_ for the general population, but for atopic (read: hypersensitive) children. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3070118/
I've yet to see any indication that gluten is healthy. I also don't see how "what celiacs want" is relevant to the health discussion.
EDIT: Just as anecdotal evidence, I've literally never met anyone with a soy allergy or intolerance, but know tens of people with celiac disease/intolerances, and at least 10 that are officially diagnosed (myself and mother included).
Minor soy allergy checking in. It's been diagnosed, but is minor enough I don't normally notice and and don't go out of my way to avoid it, other than not drinking soy milk or eating tofu or edamame. I likely wouldn't have made the association if I wasn't tested for all allergies when we were figuring out my much more severe peanut allergy. Perhaps there's a large population of undiagnosed people allergic to soy as well. Anecdotally, I think I've always heard more about soy allergies than gluten until the recent past, though I was kinda already in the allergy community.
I believe there are two factors contributing to the perceived rise:
1. The US has lagged behind Europe significantly in their knowledge and diagnosis of celiacs disease/intolerance, so more people are finally being diagnosed.
2. The wheat in the US today is significantly different from the majority of European wheat [1]
This is purely anecdotal, but I (22) know a lot of people in my generation who easily get stomach aches from milk and gluten. I've had some problems myself. Really kinda sucks.
Soy allergies according to CDC are about 1.2% of general population. This makes it about twice as common as celiac disease (from NIH numbers) https://www.ncbi.nlm.nih.gov/pubmed/22850429