Well, generally, we know why certain models work on certain types of data. But picking a proper model and hyperparameters requires some insight/knowledge about

Well, generally, we know why certain models work on certain types of data. But picking a proper model and hyperparameters requires some insight/knowledge about the properties of the data itself, which is the whole purpose of doing ML experiments in the first place (to gain knowledge/insight about the data)! However I do agree that we don't fully understand the area yet or the reach of its applications.