As a former Action Replay hacker, I would like to say that it's not necessarily hurting much at all except your game and your DS. I was one of the ones who only ever hacked AFTER I beat the main game, and I did it because it was fun. It renewed the game, and the fact that Pokemon wasn't that hard either way made it so that I pretty much don't care about hacking it.
Within my lifetime, I've done a lot of walking. I started my journey walking on a little path called Route 1. Little did I know that walking down that route would lead me onwards to a road that went by the name of Victory. Just west of Victory Road, I walked up an entire mountain where atop stood a silent trainer who was one of the mightiest I had ever faced. I've walked, through sandstorms, across the hard desert of Hoenn. I've walked through pelting hail, across the snow covered terrains of Sinnoh. And now as I look back on all my travels I find myself walking across the Skyarrow Bridge of Unova. It took a lot of walking through tall grass patches to get where I am today...But it was worth the walk.