Hacking is good. Very good. I advocate the use of Action Replay whenever possible (which is basically all the time).
Running through walls is tremendously fun. That said, trudging through the swamp that is the Mystery Zone is not so fun. But it's pretty nifty to be able to walk behind the counter in the Pokemon Center, just for fun times, or to walk--actually walk--from Cresselia Island to Darkrai Island, just because you can.
Hacking Pokemon is even better. Having a shiny Buneary with Huge Power, Extremespeed, Superpower, Shadow Force, and Explosion is just plain awesome.
Hacking is the best and don't let anyone tell you otherwise.
Just show some common courtesy to your fellow battlers and don't take illegal hacks (such as the aforementioned Buneary) into battle without the other person's knowledge because that isn't cool, nifty, or awesome.
If all you do is hack max TMs/Berries/IVs for non-legendaries/other stuff you can actually get through non-AR means in-game, then go nuts and don't let the crybabies who baww because you're doing it the "easy way" discourage you from using AR. You don't judge them for their choice; they have no right to judge you for yours, especially since you paid ~$20 more than they did to purchase the AR in the first place.
It's just two roads to the same destination.