These days most of the classification problems in several fields like computer vision or data analysis are tackled from a machine learning point of view. This turns out in solving most of the time an optimization problem without considering any implication with probabilities or defined complex pdf models. A few years ago this was the main trend. Pick a problem, shuffle with EM and some pdf mixture, add time, form a markov chain and here you go. This seems to have completely disappeared now, leaving space to the complete opposite: find a function and solve for it. What is your opinion about that?