I bet you don't even realize you're cheating anymore. Maybe you don't do it because you've geared out of the need for it. But I bet you've done it before. You probably had someone explain it to you, this little trick of many tanks.
It's a pretty common one. I'm sure everyone has done it. It's not as if it is complex, just a simple little exploit of the pathing and casting AI. Messing with the two, using the simple interaction of the two mechanics to avoid damage and manipulate pulls.
Obviously I'm referring to the use of Line of Sight breaks to draw casters and ranged enemies closer. It's not a 'tactic' or 'creative use of game mechanics'; it's an exploit and it's about time Blizzard cracked down on it.
Don't believe me? Think about a similar situation. If you're flying and you aggro a mob, what happens when you fly away? It resets. It recognizes that you are no longer a possible target and resets. It doesn't run around madly trying to get range that it cannot, running headfirst into your waiting allies. Can you imagine the speed of the ban if someone flew around to aggro a zone, without getting hit, and then led the whole pack into a few frost mages? And yet, that's more or less what you do with every LoS pull.
Ever seen a mob "evade"? It sometimes happens when you pull and then go to somewhere they cannot hit you, such as a higher or lower level with no paths. Just like an LoS pull.
I don't think a blanket ban of all players who have engaged in this behavior is the solution. Certainly a few should be made an example of, but much of the fault lies with Blizzard for allowing this AI bug to remain unfixed for so long. It's high time they acknowledged the problem and dealt with it.