One business accessed another's computers without authorization and profited from it, to the other business's detriment (which is now conducting business with paper and pencil). Why does it matter that the businesses are in the entertainment industry like Sony Pictures Entertainment, which also had a recent high profile network security incident?

In all major athletic leagues, this behavior is never treated like a crime. Players have their careers ruined by intentional assaults. Players take illegal substances to enhance performance relative to others. High profile games are won and lost based on violating league rules. These are all forms of cheating that cause material impact on other members of the league. They are never settled by Federal Prosecution. What makes this "hacking" case materially different from those others? Only the fact that the federal government has the right to get involved if a computer is accessed without authorization.

A guy was completely careless with his password, and a competitor used it to steal information. The analogy to "stealing signs" in baseball is almost perfect. In one case, we laugh. In another, the guy goes to federal prison.

You're still saying that a crime shouldn't be a crime just because it happens to be committed in order to cheat at sports. Should I be able to get away with theft if I'm just stealing some other team's sticks and balls to make them play worse?

That's the typical attitude on communities like HN re sports. Even though the computers may contain trade secrets worth millions (for instance, trade discussions), it's worthless because it's a game. However, if their Github was hacked and someone stole the source for their Rails/Bootstrap startup that's an AirBnB for Umbrellas, it'd be the crime of the century.