I used to play Metal of Honor with a bunch of friends and one of them 'tweaked' the game with some mods. Like unlimited grenades, scope to handgun etc. We all played with the same mods and it made for some pretty hilarious game playing but we always agreed on the rules before the game.
Most of the time we played 'regular mode' game sessions but once in a while it provided a different change of pace (mods).
It all depends on the situation, I think mods/hacks in the proper context are ok.
As far as 'cracking' goes, this is a different issue. I myself have cracked some games only to realize in 30 minutes or less there is no way I would shell out $75. There is so many bad games out there, I empathize why ppl crack them in order to try them before they buy.
I know some ppl who might say that is what demo versions are for. But have you ever tried demo versions? First of all, most of them are stripped down versions so you really don't get a good experience/impression and second of all they are usually not compatible with the full version games your buddies bought (that they insist you have to try out) so you can't play multiplay together which might lead some ppl to crack games in the first place.
IMO, until they (gaming industry) lower the price of games to be more accessible to a larger market I am certainly not taking a hard stance against game software infringment.
Sincerely,