This makes sense, but...
Won't this lead to ridiculous kiter builds?
Also fighting critters is very run speed dependant - the most dangerous critters are the ones that can keep pace with the player (Alien Matriarch, Deathclaws, human enemies, centaurs and floaters, geckos, etc) while the weakest are the slower ones that lack some uber ranged attack or HP bloat (normal ghouls, radscorpions, wannamingos, mantises). The only exceptions to that rule are slower enemies with strong ranged attack and HP bloat, like Super Mutants and the odd well-armed and ridiculously tough ghouls from hell that pop up in the Core sometimes.
So anything that messes with Run Speed is a lot bigger than what it seems, because it messes with both PvP and PvE.