The problem with that complaint is that "What will happen if [...]?" is what physics is good at answering, but "Why does [...] happen?" is really beyond the scope of the field.
Fair enough, but understanding why something happens is surely within the scope of science. I get the predictions are the primary goal, but that's a lot easier if you understand why. For example, Einstein told us why gravity happens. That made it much easier to predict the orbit of Mercury.