The Academy of Motion Picture Arts and Sciences recently updated "the rules"* for animated features:
In the Animated Feature Film category, the rule governing running time for a motion picture to qualify was changed from at least 70 minutes to greater than 40 minutes, which is consistent with the running time requirements for feature films in all other categories. The running time for a motion picture to qualify as an animated, live action or documentary short film has been and continues to be a maximum of 40 minutes. The previous 70-minute threshold for an animated feature had left a gap for films that ran between 40 and 70 minutes, effectively preventing them from being able to qualify as either features or shorts.
Also in the Animated Feature Film category, a sentence regarding motion capture was added to clarify the definition of an animated film. The language now reads: “An animated feature film is defined as a motion picture with a running time of greater than 40 minutes, in which movement and characters’ performances are created using a frame-by-frame technique. Motion capture by itself is not an animation technique. In addition, a significant number of the major characters must be animated, and animation must figure in no less than 75 percent of the picture’s running time.”
Now I agree with them on the 40 minutes or longer for 'feature' films, seeing as how Archon Defender is 65 minutes, so under the old rules it wouldn't 'technically' qualify as a 'feature'. (heh.. they must be getting ready to give me an award of some kind ;)
In terms of motion capture, that's just another tool to use in animation. Think of it as being able to 'paint' movement. You can't disqualify a painting by one of the masters such as Dali or Van Gogh because they used a particular brush to paint their work. Nor should you disqualify an animated film simply because a certain type of tool was used to make that animation. Motion capture is a great tool for an independent / solo animator to use, and there are lots of free motion capture source files available online as well. A good 3D animation program will also allow you to save your animations out as motion capture files to use again in other scenes, and have a way of blending those motions together and modifying them.
Plus if any of my own experience is anything to go by, the amount of effort that goes into 'cleaning up' mocap data so that feet don't slide and that body parts don't ghost through each other, it pretty much ends up being all hand animated in the end anyways.
* This is the internet, you can ignore the Academy's "rules"