I have very mixed feelings on this one. Yes, I want them to be more open about what they are doing. I hate that bots impact the leaderboards and discourage honest players. I want to at least see some evidence of action against botters!
On the other hand, I get why they don’t discuss the security measures they are working on or the lawsuits against bot makers - until the hammer drops. It only gives the bot makers a way to evade and adapt. Of course, some are outside the reach of US law anyway 
I think you really really really underestimate both the player base, and the number of people who engage in nefarious activities.
Third party sites usually operate outside the reach of US law. They are criminal organizations, not just a few kids in a basement.
-They use phishing, malware, and virus software to compromise real player accounts. Real players who are very upset about that.
-Game company spends real money in man hours to have CS assist and at least recover access to the account, if not the lost items.
-Server resources used by bots and the impact that can have on real players - lag, etc.
-Ongoing costs for a team to deal with security issues
-Legal team costs to go after them
-Financial compromise by giving third party sites info (yes people do that). For some reason the players don’t blame themselves though. They associate it with the game.
-Game balance around trade. Gear curve is set to prevent everyone from gearing too fast. Setting in game drop rates is easy to control. Outside systems like trade muck with that. We saw how bad that was in D3 Vanilla. This makes players very angry, esp when they want to find loot.
Someone else making a few bucks off a game is not that big a deal, even if it is illegal to profit off IP you don’t own. It is all the negative impacts on real players, and the costs to the company to combat and fix that. In the end they just limit things.