Right now bows are pretty crippled by having a low and non-increasing attack value. Against someone with good armour they really don't do much at all unless you are using Curse or the 66% AP longbows at the end of the tech tree.
Are Archer units useful and good to have? Definitely, I always build them. They're great for killing squishier targets. But for killing big stuff they kinda suck IMO, I don't think that making them weaker is a good idea. One exception - if you can cast Stinking Mud and Mass Curse (hey Kul-Al-Kulan!) then archers become godlike.
That being said, I am all for tactical diversity, I wish that something would get me to build (other than in special circumstances) melee units other than Spearmen with the Charge trait. I am trying to get a good long game going where I accumulate a lot of crystal, and going the magic route instead of iron weapons and armour. It hasn't happened yet though as Crystal seems to be more rare than iron.
- Manii Names