I've played a lot of MMOs. The main difference between content updates in XIV and in other games I've played... is accessibility.

Content in XI would take months to complete, simply because it was difficult (no duty finder, higher challenge, actual penalties for failing, etc). For example, I remember when Chains of Promathia was released and the 3 Promyvion zones. People weren't running them on Day 1. Or Day 2. Or Day 3. First you had to farm up the materials/gil to buy the new gear that would make your job viable in those zones. Then wait for Friday - Sunday timeframe to get other people to actually run the zone.

It wasn't like new content here where we clear the new dungeon, 24-man, trial in a few hours.