Why add salt to dumpling dough? I often cook Russian dumplings - pelmeni, but it relates to any similar kind of dumplings. Basically, you wrap small balls of ground meat (mixed with spices and other ingredients like onions) and boil them until ready. All the recipes I saw suggest adding small amount of salt to the dough (about a teaspoon to 500 g of flour). What's the purpose of it? The filling is flavorful and dumplings are boiled in salted water, the dough will be flavorful enough at the end (like, for instance, cooked pasta). I never add salt to my dough, and I tried it last time, and tasted no difference, as I expected. What task is solved by adding salt?
For the reason salt is most commonly used: it's a flavor enhancer.  We're not used to thinking of dumpling dough as possessing a lot of flavor--especially when it's there to provide a bland contrast to the savory filling of the dumpling.  But salt in the dough will "make it taste more," as my mother used to say.  Specifically, you'll taste the subtle richness of cooked flour more easily than if you omit the salt.  

The same thing happens when you cook dry pasta.  Few amateur cooks salt the cooking water enough.  It should be sufficiently salty that some of the salt penetrates the pasta as it cooks and softens, so that by the time it's done, and ready for saucing, its intrinsic flavor--flour and egg--is heightened.  Slightly.

In both of these examples it's very easy to use too much salt.  When I'm cooking something new and I don't know how much salt to use I try, in tasting, to see if I taste the dish itself better with more salt without actually tasting a salty taste, which indicates oversalting.

Chocolate-chip cookies are so much more delicious when properly salted, as is, believe it or not, blueberry crisp.  Generously salting the bread crumb topping of a blueberry crisp brings out the tastes of the ground nuts, the flour, and the butter, and makes it an even more lovely contrast to the cooked fruit.