The latest illicit activity report now specifically mentions bans for botting.

[Mwynn]

3. It can potentially lock parsers out the game, but parsing is against ToS anyways.

If that happened, we had no Raiding Scene in FFXIV anymore, probably a few thousands that never will clear Savage.
Tons of Raiders not playing anymore results into a loose of Money, which SE is sure not thinking twice about it.

They could create some system that recognize legit packets. If the packet wasn't originated by a proper client, BAN.

You can't make a difference of manipulated Packets vs "Legit Packets", a Bot simply makes use of the Packets like a Player does in the end.
This begins with Keystrokes and ends with automatic responses and everything they can.

Let alone, as you said in your Post, the Client has not even a proper Detection, to make a difference out of those.
Even if it had one, it would probably take a Week if not even lesser to have a work-around for that Detection, and the next time it might be even faster if SE would use the same method.

I'm just being realistic, what's the possibility they start banning Bots? Since now it hardly happened plus not to forget, each Real Bot Player and not RMT Bots, are Real Customers like you and me.
Be surprised, some of them even make use of the Mog Station for Glamour or Mounts.

The only Bots that actually hurt Square Enix in terms of Business are the RMT Bots running on Credit Card Frauded Registration Codes, they will never extend their Gametime aswell.
How so? In 2-3 Weeks of their Lifespan, they get banned anyway, so they just repeat the Cycle and use the 30 Free Days they get.

There is no Point to even mention the RMT Bots (The Players stacking all together in front of a NPC and jumping to the next one, having a gibberish Name).
If you consider how fast one Player gets banned due of Chargeback or any Bank Issues, this Process of banning RMT Bots is likely automated on SE's Side.