The biggest thing I have against runners is that they help corrupt the natural story line of the game, by giving people a short cut to areas of the map where they don't yet deserve to be. When I get into a party to do a quest or mission, I would like to have my party members be sort of on a par with me. Not some low level who got run through the game, and not some low level wearing super Droknars armor.
This game has some definite drawbacks, one of them being that it is too easy to transfer high level weapons and money from your first characters to your lower level characters. The sweetest part of this game for me was playing my very first character, where every new quest was a struggle, and every new weapon found (also in low level areas) was a find! Another definite drawback is that you can be run through the game.
What I think would be great for the PVE part of this game is for Anet to alter the game such that you cannot do a new mission or quest until your character has successfully completed all the previous missions and quests in the story line. Add to that a level/quest/experience limit on the use of weapons and armor. This would not block high level characters from coming to low level areas to help out (which in itself, in my opinion, is a real annoyance) but would effectively force PVE players to follow the game as it was designed. Runners, of course, would then be out of business.