Friends of mine, new to the game, becoming discouraged by STORY QUESTS

[Niwashi]

Congrats, you've found a specific scenario where unlocking a series of dungeons is only done in a short period of time. Well done. Point still stands.

No, the point doesn't still stand because that "specific scenario" is the only scenario in which your point (if it were true) would have been relevant. You claimed that unlocking the first dungeon leaves you with only one dungeon you can run until much later in the story. The truth is that you unlock four dungeons and a trial in very short order and always thereafter have at least that many to choose from. Obviously, the further you go, the more other choices you also have, but you're never stuck at only one or two options.