Cracks are bad and illegal for several reasons
Think of it this way. There are people who work the crap out of themselves to make something and put food on the table. When someone comes and doesnt pay for that software, that is less money that can go back to research and devlopment to make the applications and games better than they are.
Another reason is if you run a crack and a trojan gets launched on your computer and it crashes, whos fault is it. Not the person running the site. You are. So think about the next you do use a crack. About a 1/3 of the viruses and trojans are a direct result of this.
And most places it is illegal to use them