It feels weird to hear someone say this about a series of games that is so notorioiusly filled with vamping, sidequests, distractions, and filler content. To call Shenmue narratively languid is almost an understatement. We're talking about games where the hero has to get and actually work a monotonous day job. Imagine if everytime Frodo got hungry in Lord of the Rings, they devoted 10 minutes of footage to showing him hunt a rabbit, skin it, cook it, and eat it. You could probably cut about 80% of the content in Shenmue 1 and lose very little from the overall story.
Shenmue's attention to extraneous, superfluous detail is the hallmark of the series, it is true. But truncating the story down from 5 games to 3 is probably not all that big of a deal. It's probably more difficult from a production standpoint (having to generate art assets for 5-10 different locales) than it is from a storytelling standpoint. At the end of the day, the story is kung-fu movie fodder anyhow -- not Hamlet or Henry V. If it takes you 40+ hours to do a kung-fu revenge story, you're probably doing something wrong. Even Kill Bill was kinda pushing it with 2 separate movies.