They weren't the strongest ground units in warcraft 3, in 1vs1 they lose against bear druid, dryads if you know how to micro (And they also lose against mages in same population because the polimorph and magic damage) and Mountain king kick hero tauren *** even with reincarnation. They are defenseless against flying units, I remember how fast gryphon riders kill them.
They can be good hunters, but they are very big to hide, and dwarves outnumber them. It's easier to shoot a big target than a smaller one, they would not come alive to the close combat.
If you will talk about lore, ignore the game's logic, where unarmed lvl 90 gnome can kill at a punch 100 low lvl orcs^^
If a dwarf rifleman shot a tauren, the tauren will die, if 20.000 riflemen shots 5000 taurens, taurens will die.