Never went online before X/Y, and never found a shiny before X/Y either (apart from the usual Gyrados and just one of the event legendaries before X/Y came out). Before this, I only traded with myself or with my son. Never cloned anything except the occasional evolve item in Gold/Silver (which meant cloning a Pokemon as well of course). So all this online battling, trading, IV breeding, shiny breeding etc is totally new to me. You have to remember that, although I've been playing since Yellow, I was in my late twenties then, am a lot older now and I have always played in isolation - until now. So my take on this is probably not the same as most players.
I don't approve of hacked Pokemon at all, legal or not. I personally don't give a stuff what other people do, so long as they don't ruin it for everyone else. Asking on the GTS for Mudkip (currently impossible) or Milotic or Articuno for a shiny verson-exclusive, rather than trading for the other version's equivalent (or similar), is insane. And that is the end result of hacking Pokemon. Everything available can only be traded for another hacked Pokemon. All will be shiny, all will have 6IVs, and it will be impossible for anyone trading a legit Poke to get anything decent in return, unless they've spent a million hours breeding for it or got a really lucky wild encounter - and then it will be assumed their trade is hacked anyway. So why bother? Yeah, I don't approve of hacked Pokemon.