The Loporrits won't be finished in a day.
The Extreme won't be finished in a day.
The Custom Delivery won't be finished in a day.
The Island Sanctuary won't be finished in a day.
The ultimate DEFINITELY won't be finished in a damn day, if the previous one is anyone to go about.
The Treasure and Deep dungeons are designed to be done again and again.
And Duty Support not only added actually new storyline bits to old MSQ, but also actually... you know, increases the value of the game for the new players, which is among the most important thing to do to keep the game healthy.
One of the major things about FF14 is that they add in a bunch of content and spread it out so that there's always something to do and you're not having to dedicate your entire life into doing it. They try and put in just as much for the RPers, crafters, and casuals as they do for the hard core ultimate players. Simple as that.
If you don't like it? Then by all means, Shoo. Go away. We don't care to hear your complaining.