As a somewhat new'ish player myself (I basically didn't start til recently despite buying the game years ago), it's taken me months to get through ARR, HW and I'm only partway through Stormblood. When I think of skips in games, I generally think of things that either take a lot of time but offer very little (ie- fast travel avoids having to spend most of your time auto running from point a to b- just consider how often you use it rather than walking or even using a porter which is a slow version of fast travel)- or activities that are specifically made to slow people down to make them play the game longer/spend money (grinds, most leveling systems, ultra low drop rates to valuables that can also be purchased in loot crates).

I don't think you can skip to the end of a story and then come back later and have the same effect- and the reason all the group content is behind story is because the story leads up to everything you do, it's interconnected. You ruin the dramatic effect of Episode V if the first scene you ever see in Star Wars is the father reveal, you aren't surprised if you know who dun it before a who dun it starts. You can't go back and unknow things, and generally speaking most story writers- whether for games, books or movies- want you to experience it in a certain order.

Now, to me the MSQ and major side quests is the biggest draw of the game, so spending a long period of time doing it is entirely to my benefit. I can understand wanting to skip a grind, or skip some sort of repetition- but by its nature that's not what a story is. I just can't imagine buying a regular game, book or movie only to skip to the end.