Yes, bots are beneficial for NC. The cash flow in relation to the botters is as follows:
1. Botters farm adena/items in an automated mode (we all know who we are talking about, even NC, but NC just turns blind eye)
2. They sell adena/items for real money
3. If they are not desperately in need of rice (and they are not, as lots of them live in poor countries and one Baium 3 will feed their whole family for a year), they buy loot boxes from NC.
4. NC has money, can report to HQ their "tremendous financial results".
5. Also, bot population increases online numbers for their reports.
These people also went as far as blatantly exploiting bugs in the game (getting into castle without breaking walls or gates and casting it, for example), doing DoS attacks on those who want to stop them by dropping thousands of arrows in the farming spots or even in towns.
Problem here is that NC does not understand one simple thing here: if you will be customer-centric and not pocket-centric, you will actually get more money - listen to your customers, do the right stuff and you will regain customer base. I can bet you will - if you take a look at illegal servers and how they listen to their customers - NC is quite the opposite of "customer oriented" company. Why illegal servers have more population, more action, more interesting events, content, etc and less bots (or even none) than official servers? Even if we will take official L2 in russia - there is no bots, or at least they don't survive long enough to actually negatively affect gameplay.
Do the right things and players will chose to go to official servers rather play on some random illegal ones with uncertain destiny (wipes, etc). Turn your brain on, please, NC.
While on Giran server - I can see very same ponies in RoA and AC, for example, which I saw there more than a year ago. Exact same characters. If it was some lvl 90 with VIP100500 - I could have understood that - eventhough in ToS they write they do not allow botting, but for highly-paying customer they could have turned blind eye (which would be also sad, but it would be at least explainable).
NC, please stop killing the game. You are technically robbing yourself with this approach. You can earn much more money by doing things right.