Modding, Hacking, & Piracy, four very different things. Most Piracy requires the least amount of Hacking, on some systems they also require minor amounts of physical Modding, and those are only required to get around the securities companies have put in to try to stop them.
But I have been Hacking & Modding my legally purchased programs since I was 8 way back on the Mac SE30. My most memorable hack from years back was when I made a Firebat in Star Craft: Brood Wars spawn creep under his feet and fire the Yamato Cannon with no energy cost and anywhere on the map I could see.
Modding for me is about altering the experience of my software. Like cheatcodes in a game, sometimes I play the way it was originally intended, sometimes I want to try something else with the game, and when the programmers didn't think of something I want to be able to do I find a mod, trainer, or hack for it or figure out how to hack it in myself.
The programmers at 2Dboy didn't think to add alternate resolutions to their game World of Goo, so people use GooTools and other software mods to add that feature. Thes programs has NOTHING to do with Piracy.
AwesomeMod for The Sims 3 alters the game play, and has NOTHING to do with Piracy. Well, it can tell the system not to ask for the CD, but again, I already purchased it and don't want to have to keep switching disks between games.
On that subject, Blizzard finally realized a few years ago that their players didn't want to switch disks, so they made an update to Star Craft that allowed you to copy some of those files from the disk to the computer so you didn't need it anymore. Bliz has, for the most part, been great to the Mod Community. Even though most my mods are officially against the TOS, they don't crack down on anything unless its ruining the experience for other players.
So, please, when talking about Mods, hacks, and Piracy, try to learn something about it before you start claiming that we all just want to steal games. Most of our community are not pirates, just gamers going for a different experience.
By some of the examples people here have been giving it would be like having the ink run and smear off of my Monopoly board because our family decided we wanted to have everyone start with three random properties when the game begins, and all the other rule changes we use in the Green/Blackburn Rules.