I haven't used Spear Throwers too much, but I know enough about them to say Spear Throwers do need some changes. These guys cost the exact same amount as Galadhrim (700 resources and 120 cp). And, unsurprisingly, the Galadhrim are easily the better then Spear Throwers (as they should be. I'm not too knowledgeable with Tolkien lore, but I think that Galadhrim, extremely well trained warriors of Lothlorien, are much better then peasants that throw spears). It also doesn't help the Spear Throwers that Galadhrim can have their cost and the cost of their upgrades lowered. So if the Team wants to keep Spear-Throwers, I recommend lowering their price and cp to maybe 500 and 90 respectively.
But I'd rather them have some stat increases. Spear Throwers take a long time to attack because of their animation, which combined with how little of them there are in a group, high cp cost, high price, and being only average in melee combat, these units are mostly replaceable in all areas. Against cavalry, because of their cp cost, you can get 2 groups of Farmhands at the same cp cost, and they would have 3 times the amount of units. They are good against monster from what I remember, but monsters are rare, and there are many other units also good against monsters. I do like their ability that lets them have knockback with their throws. But the Spear Throwers don't have much use past that ability.
Maybe I am being harsh, or maybe I'm missing some sort of use for them, but in my opinion, the Spear Throwers are one of the most useless units in the game for their price. I'm surprised that not many other people have talked about them in the forums. If people know how to use them effectively, please tell me.