Even in RL, "thay" are weak prey animals. No surprise here, it's actually quite realistic.
This.
lol It's not like they're predatory animals. They eat grasses and leaves. By the Gods... if they gave the Deer talons and fangs to go with those horns, then people would be complaining about having a Deer run them down and one-shotting them...
They're weak because they are
prey animals. They're around as food for Wolves and Bears (and target practice for intrepid Archers and Destruction Mages too...

), nothing more.