EO uses byte data, which yeah can be grabbed but doesnt do much good to play with, and the use of the enums meens that if they try to get packet id’s they are only numbers. Reordering the enum data in a closed source app(where no one else has ever seen your order) can ensure no body knows the exact packets ids.
As far as trade hack and many other issues though, its not because of the network and they dont exactly need packet sniffers and hex editors to do the job. Eclipse Origins was built in a mannor that relys on the clients data to be sent honestly sometimes, which meens editing active data (which is data inside the actual app not the packets themselves) using something like cheat engine does have its ways of modifying some things which the client formats and sends on its own after tampering. About the relying on client to be honest, this is in such cases where the client can take a little of the work doing some math and checks(such as if theres a block in the way or not… i believe thats fixed but its an example) and then lets the client handle okay we cant move, or we can… and then the client after the check decides whether appropriate to send the packet. the server, trusts the client that it did its check and came up with the space is free then skips rechecking itself and then just moving the player. again thats an example of how it would work but as far as that specific exploit, i do believe since origins came around that security was fixed.
As for the tradehack, thats not exactly news, in fact its only because of security server sided like many things, where it either doesnt have a hack check(data being impossible values or a player not having the proper developer status to perform certain actions) as well as some unfinished code that ended up not performing updates on all participating players ends of what 1 player sends to the server allowing trickery… the tradehack there were a couple of fix tutorials so people couldnt scam and such like many things. Bugs even for the oldest editions of the engine sadly people still manage to find after all this time.
Again, making sure your server has the proper checks though is what makes or breaks the hackers ability to modify your game.