So we can't have World Showcase without Maelstrom? As tucked away as Maelstrom was in the Norway pavilion, changing the signage to Frozen doesn't thematically change World Showcase at all. The trolls in Frozen are no less real than the trolls of Maelstrom. Trolls aren't real. Norway is in the news a lot for religious conflicts amongst its population, but Norse gods sure aren't involved. Vikings aren't still "prowling the water's edge" in Scandanavia. There's more "real mexico" in tres caballeros than there was "real Norway" in Maelstrom. If the first thing you saw when you transitioned from FW to WS was a big fake Elsa's castle, sure, you'd have a great point. But it's not even the first thing you see when you cross into the Norway pavilion.
If you take out the oil rig/village at the end and the movie, Maelstrom could have legitimately been a Fantasyland ride.
Maelstrom wasn't unpopular if you're comparing it to Gran Fiesta Tour and the current incarnation of FIgment, but I wouldn't venture to call it popular or a great success by any stretch. Jaws wasn't unpopular either? But if you can easily make it better, why not do it?