The main bad point of running all the time is that it cuts off interactions with the rest of the world quite dramatically. This is ok if you have something you want to do and dont want to interact with others.
But for the most part on a rp server id expect people to want to interact with others much more often.
To take examples, id be much more likely to interact with someone who is casually walking down the street and bumps into me than a speed enhanced monk who zooms past running.
And of more importance to me on the last server I played on, roaming dm's would -always- ignore those running to get from place to place asap(unless it was a monster ambush which isnt much fun half the time). Whereas if someone was walking from town to town, taking their time, being cautious, perhaps emoting things on the trip a dm would pop up for fun random encounters. Perhaps have some interesting scenario that could progress into something much more lengthy.
Dont know the gaming community here though, so I dont even know if this server has roaming dm's in that style but its a big thing to miss out on. But like I say, if your doing something and dont care about anything else but what your doing, nothing lost.