Although sometimes you can't avoid to re-animate characters, its pretty useful if you have one-size-fits-all characters so that you practically need only one animation set - and because you have multiple characters with the same proportions, its easy. Oblivion does this also, though, the characters are assembled meshes. Nevertheless they apply the same boneset to every character, or let us say character class, an org or an elve are a bit different than humans in movement, of course.

Technically, it is somehow complicated, because when you use another skeleton, the skeleton information in your model file has to 100% to the skeleton you are referencing to. That means: bone names, bone amount, etc.pp. So it would be better if you have an animated skeleton file which the model is referencing to, and in the model, the vertex assignement have to stored in a new chunk extra for this bone referencing. This would require, though, very much work I think.

Regarding speed issues I could imagine that using one referenced model with this technique could be as slow/fast as that model with inherited bone set. Though, I could imagine that when the screen is flooded with one dozen or more characters that are using one skeleton, it could be faster, of course.

Nevertheless, I would like that, too.