Why would you want to play an archer with no crosshairs? In RL you can aim down the arrow, but in the game, this is not possible, so some guesswork is necessary. I doubt I could pull off half the shots I do now if I disabled the crosshairs, especially on sideways-moving targets.
You can't just aim down the arrow in real life. If you want to aim that way (eg, "gap" shooting) you have to judge your distance from the target and mentally calculate the "gap" you need between the tip of the arrow and the target. Here is a link explaining this style of archery: http://www.stickbow.com/FEATURES/SHOOTING/gap.CFM
Or, you can shoot instinctively where you focus on the target and instinctively aim the bow, kind of like throwing things. Here is a link explaining this style of archery: http://en.wikipedia.org/wiki/Instinctive_aiming
There are other methods of aiming in real life, including the use of modern bow sights that have different colored crosshairs for different distances. The Skyrim crosshair is more like the modern bow sight. It is not a primitive or traditional method of aiming, like "gap" shooting or instinctive aiming. Bow sights are a modern thing typically used on compound bows with pulleys.
There are other primitive methods for aiming a bow in real life, like "string walking" where you put your fingers on different places along the string to account for distance. That method of aiming is not possible in Skyrim.
But you can use either an instinctive method of shooting or a "gap" method in Skyrim, just like in real life. The archery in Skyrim is very realistic and well done.