I never said that they're more expensive. In fact, CG films are more often than not more expensive to produce than traditionally animated feature films.
Princess and the Frog had a budget of $105 million. It made over twice that at just over $260 million in theatres.
Tangled, coincidentally, had a whoppingly huge budget of $260 million, and ended up making almost $600 million at the box office.
My point was, traditional animation is a time-consuming and grueling effort that relies on an extreme amount of hard work. The very processes of original cell animation mean that a huge portion of development goes into menial tasks like copying, tweening, inking, correcting, etc etc.
Digital 2D animation like Flash alleviates a lot of the 'grunt work' of traditional stuff because it allows animators to work with assets and animate in ways which have the potential to cut out the middle-man, so to speak. It's one of the reasons why Flash continues to produce a lot of television cartoons.
CG is just an extension of this. The digital platform streamlines the animation process in ways which save time and effort, and still produce work which comes out looking good. As has been said a lot already, CG is also very much 'in vogue' at the moment (but I don't expect that to last forever).
All of the digital developments which increase efficiency are good things. Animators can work faster and easier, which means more movies produced at a reasonable rate. Scenes can be altered and retouched seamlessly without having to hire people to come in for a few more weeks.
But I am definitely with you when you say that 2D animated movies have a certain charm. I'm all for seeing more traditionally animated films in the style of Princess and the Frog and older movies. I just think we need to understand just how efficient the digital platform has made animation as an industry. We should respect positive developments.