Formations: why are archers in the back?

Should they not be at the front, to maximize their range in the beginning of an engagement?
Its always the tanks (!) running in first.
Should the tank not be in second line, ready to overtake the archers when needed (aka the enemy is closing in)?|||Imagine, for a moment, a legion consisting of 900 footmen and 100 archers.
Now put the archers in front. Imagine an enemy legion coming in full-force and both forces clash.
The archers have the initial advantage but lose a lot of time trying to find their way to the back in all the chaos that battle is so no, not a good idea.|||Leyline|||WNxWolfinator|||They should just add a 'reverse formation' toggle button.|||there in the back because that's just where they should go, you don't want a flat tip on a sharp blade(fail analogy) If there is some sorta pike men then they should go in front maybe 1-3 men thick followed by swordsmen and then any heavy artillery or archers or any sort of specialized forces in the rear, with a separate division for Calvary
Source: Lord of the Rings & Eragon...Jk
EDIT:
forgot to add in why,
you want the archers in the back because they aren't the strongest force to lead your group, meaning when your army meets another army and the pike men and swords men are in the rear then your archers will die immediately instead of supporting the front lines|||RoboCop|||Headless|||Custom formation configurations would be a good feature|||I would prefer intelligent unit roles. So archers DO start at the front and fire a few salvos, then move to the back as melee units come in range. With the flow field system, it'll be easy enough to have units keep X distance. Then the game world can resume with archers firing from the middle or rear of the formation.|||Starfox|||maxinator|||Headless|||maxinator|||If we're talking about an auto-combined formation, then archers should *definitely* go in the back.. (unless we're also expecting some fancy skirmisher AI+smart formations that change on their own, then I could maybe see them in the front).
I view the default formations as a 'safe' operating position. Just like in SupCom1/FA, you don't always want your shield bubbles in the middle and your AA/arty at the back, but that configuration maximizes the safety of the fragile units and coverage against all threats. It's a good default. If you want your archers to lead your ground troops, then you should micro them to be in front (just like you would do in Total War, FA or most any RTS).
Incidentally, I would love to see some flat-trajectory ranged units that were capable of shooting your own troops in the back (i.e., I want friendly fire), like the arbalests from Medieval Total War. I kind of doubt GPG will go that path, based on the trend between FA->SupCom2... but it would be great if missiles were all capable of FF *and* they gave them an AI that was smart enough to check its LoS before firing (again, like Total War).
Thus, the archer/rifle/whatever units shouldn't be stupid enough to stand there blasting straight into the backs of an ally, but they might shoot at a distant melee and hit both friends and foes due to firing randomness.|||In total war, archers can be given a skirmish order that allow them to automatically move back when threatened by enemy units.