The game costs with an Entry subscription fee $12/month.

You are told the next update to new content will be five months.

You have spent $60 waiting for the new content. $60 which could have been spent on a brand new game rich in new content, story, quests, multiplayer with friends, etc.

This is why people have a problem and "feel entitled", and justifiably so. You are in fact paying a subscription because it grants you access to new content that you can enjoy. A MMO-free-to-play does not charge you per month, and hence if that game does not update in five years, you wouldn't have any grounds to complain since none of your money was lost to negative utility.

At the current moment, you as a subscriber have been told you need to wait out five months and be expected to pay $60 minimum for the wait, knowing full well you can take that money elsewhere and are guaranteed to have positive returns on your investment, in the form of a new game or service to something else, like xbox live, PS+, netflix, etc.
The "entitlement" is quite justifiable for the consumer because the consumer can always walk away. The producer (the FFXIV developer team) cannot. Their product would go under. So while it is expected that they aren't chained to their work desks, they should also be expected to deliver content in a timely manner, because that is the ultimate justification to a paid-subscription for anything.