An easy definition of ethnic cuisine is "somebody else's comfort food." But if the ethnicity in question is one you claim as your own, then it can be problematic trying to promote a cuisine meant to be representative of the tradition underlying your personal identity if you're not familiar with and don't particular like the sort of the food cooked by your great-grandparents.
And that's my fundamental problem with most contemporary blogs and books on Jewish cooking. When a cookbook author readily admits "creating my Jewish repertoire from scratch" with recipes for dishes like Jalapeño-Shallot Matzo Balls, it's hard for me to take such a book seriously as a representation of Jewish culinary traditions. And as these dishes are not regular staples of anyone's weekly diet, they don't even represent a new tradition because they never gain the familiarity that would turn them into comfort food.
This isn't to say that the dishes made from the recipes are bad, just that they can't be taken as representative of Jewish cooking. These are really examples of fusion cuisine, which, by its very nature, is a subversion of traditional ethnic cooking.
Now one could argue that, in the age of prepared foods in 21st-century America, there are few vibrant ethnic cuisines because so few households cook on a regular basis, and special-occasion cooking demands not the familiarities of comfort food but rather dishes that seem rare and exotic. But blogs and books that promote such dishes cannot claim to be renewing ethnic cooking. Instead they offer merely food-fetish fashion whose ephemeral nature ensures that a generation hence, those truly interested in ethnic traditions will find little in them of value.