> This matters because if you have a method that is more computationally efficient, more easily interpreted, and more robust to extrapolation to out-of-domain data, why in the world would you go with DL?

One reason we will see more deep learning in electrophysiology is simply because it allows one to abstract over a good deal of statistics and signal processing, which are hard. Deep learning is being used as a black box for those who can't or don't want to understand their data.