Could've read all the manga in that time.
Obviously the series has more time to work with that Episode of Nami, which has to cram an arc into a movie. Episode of East Blue has to cram multiple arcs into a movie, so it's super rushed, so that they can just get through the major actions. It's just a quick recap to the point of seeming pointless as an actual movie experience, so I'm guessing it had a very specific purpose like getting people who aren't already keen on trying the series up to date so they can join in on watching the series. I guess they could have made the movie 15 minutes longer and left in some more flashbacks for emotional impact. Episode of Nami on the other hand leaves enough in to be a genuine experience for new fans or a way for old fans to re-experience the major moments of the arc, but still is more accessible than having to watch all the episodes.
