I don't see how archers are such a central thing at all. I've done incredibly well in some games just ignoring them entirely. Melee units are still more flexible on the whole. You can defend cities perfectly well with axemen. A ranged attack is nice, but it only damages. A direct attack can kill.
When the enemy is using archers, your own archers are about the least useful thing you could possibly use to counter them. Just assault them in flat ground, or forests as they approach you.
When it comes to barbarians as well, an axeman is more flexible than an archer. He can kill the barbarians directly, and get twice as much xp.
and despite all their strength, archers still tend to get steamrolled when high level heroes come through
Now, if you want to assault an enemy, some archers to weaken them will certainly help. But archers won't do it alone.
This isn't putting the focus on archers. This is taking away focus from melee units. There's a big difference here. InFFH, elee is pretty much the be all and end all of military. Even in FF, that's not entirely untrue. Try building a military consisting purely of melee units. It's stll going to be farmore sucessful than any other kind of single type army. And they work vey well in combination with others.
Mix armies up a bit.
On the defence, archers are king, undoubtedly. Because that's what they're supposed to do. Ranged attacks make them good at that, and also ive them some attack capability. Just as melee units have some defensive capability, but are mostly attack focused.
You can comprise a defence force entirely of archers, just as you can make an attack force entirely of melee units. But in all situations, a mixed army serves better. Archer are utterly useless if the enemy decides to start pillaging instead of suiciding on your walls. If you have some melee/mounted in your defence force, you can strike out at them after your archers firing from the city have weakened them. Recon units are especially good for this, combining fast movement and good strength.
Archers are a piece of the puzzle. not the whole thing.