The "short" answer is that the afk kicker doesn't actually accomplish anything since they solved the problem (for the most part) of the inability to login. All it does is inconvenience people. The people that are whining that they couldn't log in, are likely stuck in the past.
Other than that, I'm just going to laugh at anyone going "you don't have the right to take up the game's resources". The game is still going to be there even if we don't log out. And, actually, if you think about it, you're the ones wasting development resources trying to get something this useless implemented in the first place.
The only place the afk kicker would be useful is in instances/duty finders to get rid of griefers who afk to mess up runs.
Edit: What if I want to put up my flag for materia meld (or something similar) while I step out for a bit?
