The pavilions themselves. The aesthetic features of the buildings, the architecture, the cast members, the food, the entertainment (now lacking) all contribute to incorporating education into the featured entertainment.
Sure, some guests might treat World Showcase as a pub crawl. But others appreciate the detail and story behind each one of the nations. There are films to depict the history of the countries, restaurants with food native to the lands served by people from the nations. The American Adventure is still one of my favorite shows at any Disney theme park. One of the best examples of how you can be educated by entertainment.
When people go to World Showcase to eat, drink, or shop, there is still a cultural aspect to the location that allows for some type of learning to take place. Every time I travel through the nations I find out something new, by either reading certain stories myself or talking with cast members.
Was Maelstrom the most educational ride? No. Nor was it the most enjoyable for me. One of the underlying reasons we would ride it was that it was one of the only things to ride in WS. If there was an attraction at every pavilion it wouldn't have been a "must-do" each trip because there would be more to do. That doesn't mean it has to be overtaken by Frozen though.
And nostalgia is a tricky thing. Obviously World of Motion, and Horizons to an extent were replaced by attractions that are much more popular (in terms of wait times). In 10-15 years, it will be curious if Maelstrom is put on the same pedestal as extinct "nostalgic" Epcot attractions such as WoM, Horizons, 20K, etc
Personally I wouldn't put it on that high regard. I would grade it a bit lower than "nostalgic" but not so low that it isn't memorable.