You're assigning the wrong motivation behind those quests - it's not "bloated on purpose" to fill time, it literally is paced intentionally like that for the sake of how they want the story to play out. What you see as pointless bloat is meant to be character moments to provide additional context for the culture and personalities of these people, as well as prepare for future plot elements. In TV terms, it's the Season 2 start, where the big issue from Season 1 was dealt with (and was written as a single arc since the show may have ended after that first season) and so they need to start moving toward new things but that means taking the time to set-up new things (I think many players view the story here as one would a movie or a single-player game's story, and it just isn't created with that style in mind - Yoshi-P has even made references to how it's set-up more like TV seasons).
This may come as a shock, but the story team isn't trying to waste your time with pointless crap.
Also, I was looking more for a break down of what key narrative points you think would be able to brought into that "5 missions" limit, even with it being longer. What you would cut, what you would change, etc., that doesn't then mean that future characters or events don't need to also be rewritten or redone because the foundation element present in 2.x is no longer there, while also not having it end up being a rushed mess. I've done this myself as a thought exercise (which is why I don't find the "it could be done" to really be a worthwhile answer) before and was only able to trim out about 30% of what's there now plus eliminating the need for travel by using the technique they do now with moving you to the next location whenever it makes sense to do so - which could absolutely be added into what we have now - and it was at that point that future stories start to become noticeably impacted or elements in 2.x begin to feel really rushed.