I pay other people to "mod" my car with new parts. That's perfectly legal because I OWN the damn pile of steel. The mechanics won't get arrested because the manufacturer has no say about what will go to my car after I BOUGHT it and, therefore, it's MINE.
Now, if I pay a hacker to "mod" my game console, it should be as legal as above. I OWN the damn pile of plastic and silicon. The hacker shouldn't get arrested because the manufacturer shouldn't think they have a say about what will go to my game console after I BOUGHT it as, therefore, it should be MINE.