There's a fine line between stuff that's coded in the game that's legal and illegal. If you choose to run and eat, it takes the same amount of time to eat an item as it would if you ate it the normal away, the advantage being you can sprint and eat. The con to this is that you can't switch to a different item, you need to stay with the gapple/crapple. Also, the timing of running and eating takes a while to master, as you need to drop the food just before you start the eating animation in order for it to work, which is why I believe that most newer players dislike the idea. Now if you're using a macro, then by all means it should be a bannable offense, but vanilla running/eating is simply a cool bit of code in the game that some players can use to their advantage.