Well because it is a necessity to be quick with a short weapon.. If you would go Katana Ninja with a STR build everyone would just spam you from distance. If you use a long weapon you are free to choose either STR or AGI builds. Both are viable.
I really like 27/12 with short weapons like katana. Sure, I
might have to block twice to get in attack range -- but then I have huge attack speed and damage bonuses over them.
Stuff like 36/3 can't get in proper range with short weapons though. I still do beastly with 33/6 1h though.
back on topic -- There are penalties in place for backpedaling already. You may have to adjust your fighting style to take advantage of them though
Players move much slower when backing up, guaranteeing anyone with 5 athletics can ALWAYS catch a backpedaling player unless they very literally have 10+ athletics
When you backpedal away from someone, you suffer a big damage penalty from a negative speed bonus. If the enemy is chasing you, your relative character speeds = 0 though, so that penalty is negated.
So how do you counter a backpedaler?
*You chase them and catch them, and it is no different than fighting with both of you standing still.
*You don't chase them, and as soon as they step back towards you, you also step towards them and get a crazy damage bonus and murder them! Or they run away, in which case -- Why do you care?