It could completely be my perception, of course, but it seems like so many more people are discovering a sensitivity to gluten than has been the case before now. I'm wondering if one of the causes isn't consistently stressed immune systems, and we're reaching the tipping point of being able to tolerate other stressors. Also, see: asthma.
One theory (which makes sense to me) is that wheat grown now has been specifically engineered (I was going to say "bred," but didn't want to make a pun) to have *much* higher levels of gluten than wheat from, say, 100 years ago. Or even 50.
Because gluten is what makes bread fluffy. And people love fluffy bread (hell, I do). So what's the easiest way to make fluffier bread that people will buy the hell out of? Wheat with more gluten.
So if our bodies could handle some amounts of gluten, we haven't adapted fast enough to the new super-gluten-y wheat. Add to that the fact that gluten is in goddamn everything -- flour is used as a thickener in soups, salad dressings, even ice cream, for god's sake -- and it's not only the exposure to super-gluten-y bread products, but the fact that it's everywhere, that creates that scenario where the body just can't handle that much gluten and finally gives up trying to deal.
(Granted, I have no idea how mass-produced, pre-packaged soups and salad dressings compare to those from, say, 1950. Commercially prepared soups and dressings might have had wheat as a thickener back then also. But in 2012 we eat a metric fuckton more processed foods than people did in 1950. So the overall cumulative exposure has skyrocketed.)