I hack, and I see nothing wrong with it as long as you're not doing something stupid like giving your Pokemon ridiculous stats to use on Wi-Fi.
Between studying for Uni and doing all the other stuff I have to do, I just don't have the time to spend hours grinding for the things I need. At least if I hack, I get the things I want (mostly talking about TMs and money for vitamins, because I don't have time to grind money and battle tower points) so I can still have time to EV train, which doesn't take long anyway; which means I can use my team sooner rather than later.
Hacking event Pokemon is a bit weird... one part of me thinks that it's OK because not everyone gets events to go to, but another part says that that is the thing that makes those particular Pokemon special... and it should stay that way. But meh...