Pitch hack

There is also the chance that a few of those hackers won't get banned by that (if it happens) ensuing ban wave, and thus contribute more to those dreaded Meso selling sites.

The consequences of missing some chaos hackers compared to banning some chaos hackers isn't that big a deal. If this happens, as per your example of contributing to meso selling sites, then almost the same thing happens. Meso sellers to my knowledge never actually spend mesos unless it's in a transaction for real money. In this sense, they are taking mesos (a large amount of them) out of the economy until someone buys from them, when it then gets infused into the economy once again.

This is besides the point however. Like i said, deflation is never a bad thing. Whether or not you're buying from a hacker is a completely different conversation.

Everyone's damage going up all around is not a good thing at all.

Only if you're an old player who isn't aware of the fact that power creeps are inevitable in every MMORPG, and still holds the belief that everyone else getting stronger more easily undermines your achievements.

For everyone else, getting stronger is never bad unless it's a ridiculous increase like the PYPQ glitch. The only way it can possibly be bad is lack of a challenge, which isn't much of an issue with the way this game is made.