I don't know why anyone would rush end-game in FFXIV, it's just gear grinding and tome farming, seems a bit silly to get into a casual story-focused MMO RPG and then rush past the story to do... end game trials? Raids? How would letting sprouts play end-game content ahead of time do anything to help the story being long? The current raids for example are all SUPER story heavy and all involve the lore we've built in the last 2 expansions, letting them play that content without unlocking it via story doesn't make any sense to me.

Is it just to let potential players experience what raiding is like in FFXIV to hook them in or something?

Because if they hate the story so much can't they just buy an MSQ boost or something? Seems like there's already a solution for people that want to play FFXIV but not the storyline.