Why The Hobbit Battle Of Five Armies does great fights but bad battles

I've just seen The Hobbit BOTFA and there are some truly extraordinary fight scenes. Inventive, jaw-dropping, eye-watering and pure brilliant.
Without giving too much away, what Legolas does is stunning, while the use of Battle Boars, Moose, carts, trolls and the rest is amazing.
But, and here's the but, the battle tactics are so dumb!
I nearly hurled popcorn at the screen at one point.
The dwarves form the perfect shield wall, bristling with spears. Perfect, I thought. Stick elven bowmen behind that and the orcs would be slaughtered.
But nooooooo.
The elves jump OVER the shieldwall to fight man-to-man! Or elf-to-orc, actually.
It drove me crazy!
They are outnumbered but have the best bowmen in the world. Why not pile up the orcs with your bowmen and then use the dwarves as a perfect bulwark for the human pikemen?
If they had fought with an ounce of brains, they wouldn't have needed the eagles, they would have formed a barricade of the dead orcs and then the orcs could not use their numbers and would have been compressed and slaughtered.
Obviously it would not have made for visually compelling viewing, and there would have been less need for death or glory charges.
But that's the point of battles. You don't have to look good to win. You just have to win.
Still, at least it was better than having Bilbo hit his head and miss the whole bloody thing!
So, go ahead and enjoy the individual fights but remember, they could have won the battle so much easier, with so much less loss of extras!