The issue isn't the tactical ramifications of being disarmed, it's the fact that your weapon gets flung into the most obscure corner possible, and sometimes out of the level entirely.
If I were designing this, I would have made that shout rip the weapon out of the target's hand and put it in your inventory. So if you get disarmed by a draugr, after you kill it then it will be carrying your weapon.
Ripping the weapon out of the hand to put it in the inventory? That would be a total rip-off of a shout. They just need to find a way to keep it from flying into The Void.
Though, the entire concept of draugr using the Voice is questionable in itself. Are we to assume that there's roughly a billion Dragonborn from another age, and they all hate our guts for no reason?
No, they aren't dragonborn. They are dragon
worshippers, who gained the power of Thu'um in a pact with the Dragons, to whom Thu'um comes naturally - A deal with the devil. They get super-awesome shouty abilities in exchange for the worst case of insomnia ever.