Hard and soft tacos each have their place. For the make at home variety crunchy is typically the way to go. At Tex-mex places I'll occasionally get a crunchy taco, usually if it comes with a combo I'm interested in. Mexican tacos are obviously soft. I think the disconnect for me is using crappy flour tortillas for soft tacos. The store bought variety are generally too big, too thick, and too tasteless to work right. All you taste is bland tortilla. Really good, hand made flour tortillas are fine, though. And of course for Mexican tacos they have to be corn.