I don't think there is much more to say.
As of first, it is not quite a script based feature, I'm afraid
The ability to run (fast) just makes the game all the more natural.
Running is one of the most common and standard features in games right now. It is just a step up from walking, to be precise.
Plus, wouldn't it be a little tedious having to walk or slow jog everywhere?
This would also completely rule the VC Marathon out, as well.
This is a RP server, so you shouldn't be needing to shoot all the time. Also think about the criminal's side of view. It would be too dull if they had to make a dramatic slow motion walk from a burning building or when escaping from the grasp of the law.
If you opponent runs away, chase them! You can shoot faster than they can run!