I've never played another game in this style, but didn't Xenoblade have unique music for each area? I know this and Xenoblade were compared to each other for a bit for being similar.
I can make a couple comparisons to other open world games. Not the first Xenoblade, since it wasn't necessarily "open world." It's actually a pretty linear adventure, but the huge areas with tons of quests in them cleverly disguise this. (Also as a note, linear is not bad on its own, and is quite good when done well, see Xenoblade.)
Other comparisons to make, though:
Xenoblade X - Each region has its own theme that plays while you're in it, with a night and day variation. The city of New Los Angeles has its own (completely shitty) themes, the named overworld areas have different themes, and there's even music for caves.
The Elder Scrolls IV: Oblivion - This one's a bit interesting, because the entire overworld, nature and towns both, use the same music... but it's a handful of tracks that cycle through. They're not short tracks either, they're decently-long compositions. Caves and the planes of Oblivion have their own theme, though.
I'm not really against what Breath of the Wild did, because the actual music that is there in like towns and stuff is quite good. I wish the little notes that played were a bit more present... but at that rate they might as well be full-blown music. A Xenoblade X approach to music would have been fine I think. Distribution that is; I don't want Sawano anywhere near Zelda.
