As both a traditional and CG animator, it's hard to say one is easier than the other. I tend to believe that traditional animation is much more tedious and time consuming, but it's not like CG is a walk in the park. Here's a rudimentary breakdown of how each method would approach a scene in a film.
Prepping the backgrounds:
CG: A set is built and lit, once. The camera can be changed at any moment during production of the scene. This set can be used multiple times.
Traditional: The layout, lighting, and camera angle are agreed upon for each shot, and a background artists paint the scene. This needs to be done for every new shot.
Prepping the characters:
CG: Lots of time spent modeling, rigging, texturing and mapping a model. But you really only do it once at the beginning of the project, and it's usually not done by the animator.
Traditional: Not much to do here beyond the design of the character. Nothing created during this phase will ever be seen by the audience.
Animation:
CG: Animation takes time, but iteration is quick. And you only need to do keyframes.
Traditional: Animation takes time, and iteration means you might be redoing a number of frames, if not the whole scene. Depending on the complexity and speed of the motion, the lead animator could be roughing every frame. Even within a single frame, iterating something like a leg would require redrawing several joints, whereas you'd be moving a few dummies in CG.
Inbetweening:
CG: You watch the computer do it. The character is always perfectly 'on model' (looks exactly as he should.)
Traditional: You painstakingly tween every frame. This is normally handled by a team of animators who have to work very closely with the lead animator to make sure each drawing is on model. A single mistween can break the illusion of the motion, and depending on the amount of time between keys, could mean a lot of redrawn frames.
Rendering:
CG: Lighting artists prepare the scene, once, and then the computer renders it out.
Traditional: These days every frame is manually cleaned up and colored digitally, at least we aren't using cels and paint anymore. Well, us sane ones anyway. It's extremely tedious either way. An artist has to manually clean and color every line, fill character with appropriate colors, and through various methods apply shading, which itself had to be hand animated.
Compositing:
CG & Traditional: With digital tools, this is where the two are actually pretty similar. Just a matter of layering the artwork. There's more manual work with traditional, particularly if the camera is really dynamic, but otherwise the steps are nearly identical.
As you can see, CG requires more prep work (modeling, lighting, etc), but once those assets are done, it's relatively quick to push out scenes since the computer handles a lot of the dirty work. Traditional animation pretty much requires the same amount of work for every shot, it's not like you can create a set of assets and reuse them over and over again (without looking cheap.)
The biggest difference between the two, for me personally, is the ability to iterate after a sequence is complete. Don't like the camera angle used? Wish you had given your lead a bigger jaw? Decided to backlight this scene? If you had done it traditionally, there's no easy way to make these changes.
They are both great artforms. It's unfortunate that there's this perception that traditional is somehow cheaper and easier to do.
