memory consumtption is an issue of morphing (vertex) animation
but there are even more important dtrawbacks
#1 animation blending
You can blend two animations but it is not that easy
#2 animation transfer
You can not transfer the same animation to other modes ( ex .bvh files)

On the other hand I doubt that skeleton animation is a good solution for organic animation even for prototyping
You must use a lot of bones
In my opinion the best solution is to mix skeleton amd morphing animation in the same frames
The former for general movements the latter for details