I think that's close to it, but not actually the truth of it.
Don't forget to add finding the Map Fish to almost every single tile.
It bugged me over time and it
really bugged the Hell out of me in Ocarina of Time, but I think the real diminishing joy from the Zelda series harkens back to LttP again. Back when the Overworld was itself a massive mega-dungeon full of incredibly fun bonus rewards and challenges and stuff.
What bugged me about Ocarina of Time was that the world was hollow. Exploration almost always yielded nothing of import save for Heart Container Pieces. If you were really astute, you could find an extra shield or a bottle or something, but who cared? Ocarina of Time was easy for it's time and money was thrown at you faster than you could ever hope to use it, particularly since, surprise, there was nothing to use it on.
Then Majora's Mask hit and somehow, we had a Zelda game that "got it." What was that it? All the extra stuff. All the extra powers and side-quests(many of them better written and more interesting and powerful than the storylines of entire Zelda games, past or present.) The extra masks, many of which actually gave legitimate tweaks and benefits! I can't recall entirely, but I also believe they actually expanded on the use of money a tiny bit and thus that held more weight as well.
This brings me to that map above. I felt Wind Waker was a bit of a compromise. The ocean
was not as tedious or empty as many people feel, but it creates an illusion of such because it was about half as empty as you thought. Doesn't make sense? Consider, say... the Beedle Boat Shop. How many of us actually went for his SUPER BONUS MEMBERSHIP CARD? It was a bitingly clever joke and parody, but it was ultimately hollow: your money was next to meaningless and never really needed and the things he sold you weren't all that important unless you were some sort of clown who chronically ran out of basic materials. And those were probably in bushes anyway.
There's a world of difference between finding a new Mask, killing a Biiiig Octo, and discovering an interesting island vs... another heart container piece(which is a terrible focus of exploration, in my opinion. Your brain eventually begins to figure that only one in every four discoveries was worth the time.) I think that's the crux of it.
So more Majora's Mask. More options. More things that aren't strictly necessary to beating the game, but can satisfy a wide variety of curious players and play styles! I want to see a map like the one above with an extra 50% of the nodes colored in with [FANTASTIC GAMEPLAY ITEM]!