This is news to me, because I have yet to see any of the coins being recovered from 100s of Bitcoin exchanges and services that got hacked in the past. One possible reason why these people were caught, might have been that they used fiat conversion services that helped to identify their true identity.
One way or another, the main purpose of these criminals is to convert back to fiat. If you manage to partner with as many exchanges and services as possible, you gain a massive advantage over these criminals.
The goal is to make these criminals have less options to sell their coins at, and whenever they sell these coins through the OTC market, the innocent people buying them will have some explaining to do at some later point....
As for the coins coming from exchange hacks, as long as the hackers don't touch anything that's centralized, there isn't much that can be done against them, so it's pretty much a waiting game.