CG is really a synthesis of sculpting, painting, film/photography, and programming.
Like sculpting, you need a firm handle of spacial conceptualization and perception. If you have a hard time visualizing the shape and curvature of something the human clavicle or the texture of a worn leather belt then you might have an equally hard time with CG. So much of what I do in CG boils down to, "Can I see it in my mind? Can I virtually 'feel' it on my fingertips?" In a lot of ways, it's like an actor asked to eat an imaginary chocolate bar. If he can't taste it then he can't fake it, at least not convincingly. If you're a good sculptor then there's a good chance that you'll be a good CG modeler. I can't draw to save my life (pencil woes), but I'm an excellent sculptor. That, for me, translates into an equal level of CG proficiency.
CG is also like painting. To texture and shade, you need a firm grasp of where your light sources are coming from, how the surface is absorbing your colors, composition, color juxtaposition, etc.. You don't necessarily have to be a good painter to do CG, but it certainly helps. Like anything else, I think that you can pick up texturing skills. The harder it is for you to grasp color/texture theory the harder it will be to grasp actual surfacing.
If you're into animation or complex stills then the similarities between film and photography should seem obvious. I'm not saying that you have to be great at either, but you should have the ability to observe. Good animation boils down to 50% observation and 50% perspiration. It's like that one friend who always knows what you're going to say before you open your mouth. Is it because he's psychic? Nah. He knows his subject and he knows how to read the subtle cues. That's all animation is. The longer you observe something the more you can understand the nuances of weight, balance, pacing, and so forth. That's why many animators keep mirrors and video cameras around. A good animator is also good at observation.
The LEAST of CG is programming. You may encounter the need to write a script now and then, but unless its your job you won't regularly encounter them.
Many people are under the misconception that CG is technical. It has technical aspects, but it is still art. There's no "Make Cool 3D" button. You don't have to be an engineer. Heck, some of the best CG artists I know are the least technically minded people. The best CG art is still made by those with an eye one the classic elements like space, composition, color, perspective, and so forth.
CG is just another tool. It's not different than a chisel, paintbrush, or pencil. Its there to help you get the ideas out. CG may shortcut some of the things that our forefathers grunted through, but its no an art form. If you struggle in CG then there's a good chance that you'll struggle with non-CG arts.
BTW, very little about that chart is factual. Having done CG for 18 years, I can tell you that that chart is very subjective. There are inconsistencies, inaccuracies, and biases all around. It is very much skewed toward the Autodesk end of the spectrum. There's a reason why the chart didn't compare all the apps at their NON-base levels. Maya & Max don't exactly rule without a fight when you've got XSI & C4D with their non-entry level (newbie friendly) models. The playing field is much more even then and far less happy for Blender users.
Autodesk really doesn't make entry level of Maya or Max. Not really. They make pro versions and studio versions. That's the real difference between Maya Complete and Maya limited. One supports the needs of a full studio. The other doesn't, at least not as much. There is no newbie version of Maya. The PLE doesn't count since you can't save and have to deal with watermarks. That's where C4D and XSI differ from Maya. C4D sells the "core", which is basically the main app stripped of all of the advanced functionality. So, when an article as dumb as this one compares C4D Core with Maya Complete the comparison is apples to oranges. The comparison can't be made. Just because Complete is the lowest available version of Maya doesn't make it an "entry level" (read: stripped to basics) version. It just makes it THEIR entry level point.
BTW, if this was REALLY complete discussion of the apps then Houdini probably shouldn't have been left out of the picture. Just my $0.02 on that one though.