The game definitely needs a questing overhaul.

I don't think "starting at level 50" is necessarily the best way to achieve that, though. Rather, I would go through the entire MSQ and remove as many quests as possible, that don't directly contribute to the story. Make them separate, standalone quests if need be. In addition, maybe consider adding a means of quick-traveling to your next quest giver, or at least for turning-in quests. Eliminate as much "running around" as possible, like I said, unless it's directly contributing to the story (just avoid cutting out characters entirely, where possible).

Personally, I might even go so far as to add a new "Starter area" entirely, which has a more expedited storyline. Maybe you start in Mor Dhona, your quests have you dealing with more of the "highlights" of the story, without getting bogged down in stuff that doesn't really matter (ie. Cid losing and regaining his memory; I really don't feel like that really added anything). That way, you can still choose a different starter area for the "classic" experience, but if you just want to catch up quickly, it just kind of gives you the cliffnotes version of the story.

As someone who recently got several people to join FFXIV, I definitely could see, they both have struggled to stay interested in the game. One of the two bought a level-boost and story-skip, and struggled to get used to the combat (because for him, MMO's are about "dungeons & raids" and he didn't want to spend weeks or months 'catching up'), and for the other, she followed suite but is now bummed she doesn't understand the story and can't really experience it unless she starts all over again (even the unending journal, it doesn't really give you context for the cutscenes that play out).