You're right about animation houses cutting down on animation frames in order to save time and money, and I think that this is an area in which CGI can be used very effectively to enhance the fluidity of the animation (interpolation?). More generally, CGI is able to tweak and enhance traditional animation in a number of ways that improve the visual fidelity. Using CGI to enhance traditional 2d art techniques is a good thing, providing the CGI is employed subtly and in moderation.