Hardly "hacking," and I have a difficult time understanding how that is at all fraudulent. What am I missing?
The reason the FBI is involved heavily is because virtually all identity fraud is related to organized crime and money laundering, the rest are usually linked to insurance frauds. Being the first real case of a major identity fraud online, I wouldn't be surprised if the FBI tries to put their heads on a pike as an example to everyone else.
Immaterial of what they did it for, identity fraud is taken as an exceptionally serious crime and as far as I could tell, they performed a thousand or more 'unlawful identity changes' by operating bots under false names for illicit means. The one exception to this is the use of a pseudonym for anonymity, however it's a colossal stretch to claim your bot army are acting as your pseudonyms for your anonymity reasons.
What these people did seems analogous. I don't understand how the FBI is involved.
If I act like any murderer on the run, the FBI are going to investigate me like any murderer on the run. Similarly if you act like any organized crime money laundering syndicate, you'll be investigated like one!
I can see how claiming to be someone else who actually exists might be "often criminal", but that's not the only type of name deception.
For example, I know lots of people who sign the equivalent of Mickey Mouse. What serious crime is that related to?
Or, as the Wikipedians say, citation needed.