We are used to Multivariate Regression and Experimental Design (Factorial Designs, Response Surface, etc) to model data and understand predictor/response correlations and interactions. Recently, we started to look into CART and TreeNET learning models. The latter approaches seem to have better predictive ability, primarily through improved pattern recognition. With the presence of these newer machine learning models, is there any justification for continued use of conventional regression approaches? Any thoughts would be greatly appreciated. Thanks.