The reason I went for the standard tree meshes is simple, I thought it was cool how it was random trees moving. Sort of like the forest is moving, if the trees are different from the others then it no longer has the effect of the forest is moving because the don't look like the rest of the forest. That is just my opinion though, if enough people say they want trees like the ones above then I'll see what I can do.
Now regarding their arms, it would be extremely hard to make any tree that has arms actually attached to it's body like the santas or yetis so i took the easy way out. Although, it I made all the trees fatter then the branch would start inside the tree and look more like what you want.