That is exactly the problem, IMO. You start attracting the wrong kinds of people to a mature simulation game like Gran Turismo. With the ditching of online mode, I don't think it's much of a problem anymore, you won't have to deal with these people. However, this will still attract these drift posers and all around wannabes to not only GTP, but to future versions of Gran Turismo.
I have yet to see any indication (screenshots or other wise) that this "drift" mode will be in the final version of GT4. If it is, I hope it stays a very minute mode and won't interfere with the overall gameplay.