I think it's because weapon reach is key until you are in close combat. The strike rank rules assume that the combatants are not in close combat. Once in close combat the rules state that the person with the higher DEX rank will go first and that any parry attempts by people with long weapons are difficult.
I'm not too worried about the person with the most reach going first. I guess the combat scenarios would look like this:
Mark and John have weapon skills of 70% Mark draws his sword and rushes at John, who has a dagger. Mark swings and John has 70% chance to parry. He succeeds and steps close. John stabs at Mark and he only has a 35%. In the next round Mark can give up his attacks to try and move back. John can also dodge or parry to move close and attack normally.
Unless he wants to be toast, Mark has the option of disengaging, knocking John back, taking a spear, or just hoping that John's dagger breaks after parrying a few decent attacks. Of course he can also learn shield and block at his normal chance. This seems to be one of the most overlooked advantages of carrying a shield, that and the weapon breakage rules punish constant parrying.