Ok, we've all seen it, we've all know people that do it to some degree, so here is my question. Do people really think that chanting "gogogogo" at the tank is gonna make us move any faster? I can tell you right here and now.....No, it won't. If anything, it'll make us slow down.
Here are a few key things that dps NEED to realize about tanks.
1: Tanks don't wanna die.
2: Tank want to keep healers happy. Happy healers = better heals (generally speaking)
3: We all know that mobs do different things. Part of a tanks job is to set up a pull so that it is easy to round up mobs or set up for any needed CC to keep the healer from burning through mana and keep people from dying.
4: If we were just in a large group fight, chances are we popped a cooldown. If we are just sitting there, we might be waiting on it to cooldown or maybe to let a taunt come off cooldown. If this is the case, we aren't moving until it does.
5: And this is a big one, WE WATCH HEALER MANA!! If the healers mana is low, I can guarantee you that we will not move until the healer has mana again. Why? See item #1.
Also, if a dps uses the "gogogogo" method to get a tank to go, and he/she doesn't move, pulling for the tank...well.....lets just say more times then not you will find yourself back in queue for a tank. Which these days, if you are looking for a tank for your run, you'll be waiting awhile.
If you just wait and let the tank go at his/her own pace, you will find that you will have a much nicer, smoother and more productive run. After all, which takes more time, a tank that goes a bit slow and you one shot everything? Or a tank that is rushed, makes a couple bad pulls (or the dps does) and you wipe a couple times, wasting time running back in and to where you left off? Hmmmmmm? (Pssst, here's a hint. The second one will take longer.)
Keep this in mind next time you run a dungeon and spread this information around and who knows, maybe you will see more tanks coming back out to play more often.