You don't think you'd have an easier time shooting a target 10 feet away then one that's in your face and messing with you?
Easier to hit a stationary, inanimate target at ten feet than a melee combatant "in my face"? Sure! But that's not really an applicable comparison. The situation, were it to be played out in the real world, would be a lot more complex than that, and would rely on a number of things, including but not limited to:
- Is the archer also a trained melee combatant? If so, their instinct will be to attack in a way that will firstly block or nullify the enemy's attacking weapon and cause the enemy damage as a secondary effect. That would suggest something like shoving the opponent's weapon aside with his bow arm or dodging back away from the weapon simultaneously with loosing the arrow. To hit a moving target you have to move as you loose anyway - no big deal there.
- Does the archer have an arrow nocked? If so, drawing and loosing is a matter of a split second of opportunity; if not then a new arrow must be drawn and nocked - an action at least as difficult as drawing a sword or other melee weapon. Given the choice between taking out a melee weapon or taking out an arrow when engaged in melee combat, I know what I'd do!
- Is the melee combatant well trained in melee combat? If they are they will want to do just as the melee-trained archer, above. They would try to neutralise the archer's bow while secondarily striking the archer; this would suggest an attack on the bow or designed to deflect the bow from a potential attack on the melee combatant.
How does all that map to "free attacks" or "penalties to the to hit roll"? I have no clue.
That is your opinion on the matter. It can still be lethal, but IMO it won't have its full potential for tissue damage without swinging room.
A sword is a subtle and lethal tool for killing - you don't swing the ruddy thing like a wood axe!
More prosaically, any serious melee attack should act to both block, deflect or evade the opponent's weapon
and strike the opponent as part of the same fluid motion. Swinging a weapon in a big arc will serve to telegraph the path of attack and present an opening the size of a barn door for a counter. In other words, it will get you killed quite surely and quite quickly.