Why should Model Aircraft be unstable? Meet the moment of inertia

Physics is not my strongest subject, but while playing around with a pencil in my hand, I started wondering what's wrong with the following picture of a traditional setup of an RC plane:


While this might be a good setup for a fast manually controlled "trick planes", the end result of concentrating all the weight on the center of the plane makes it more "unstable". Simply put if most of the mass of an object is located in it's center of gravity, it's easier to rotate than an object with weight concentrated on the outside edges. So especially for UAV and training models, I'd recommend a setup, where for example the batteries would be located at the wingtips rather than at the center:


This setup should allow for a more stable flight and make it easier to do automatic stabilisation. It also has the added bonus of not having to make wings as strong, as the lighter central body of an aircraft won't bend wings so much - there's a reason why big real aircraft have fuel tanks on the wings. This setup might be hard to modify on an existing model, but when designing a flying wing UAV - this is a must.

The article on Moment of Inertia in Wikipedia explains the physics behind rotating similar objects with different weight distributions. To get an easier example I recommend this site.

The plane images are originally from an article on Wikipedia, so use them if you want. And as always, if I'm wrong on this one - please correct me :)