I've played a number of MMOs over the past 17 years. It's been my experience that the Final Fantasy MMOs are fairly unique in that they have a story-based progression. Most MMOs use level as the main factor for whether a player can access an expansion. Some MMOs have a ceiling where you need to segue into group content, but most do not have compulsory group content for completing a set storyline.

I do agree with the OP that consideration needs to be put into the system for new expansions. No matter how fast someone may get through content to unlock HW now, the current progression path is still fairly daunting for newer players. And the game needs influxes of new blood to remain competitive in the marketplace.