To think that there were intentional FE undertones inserted into this game is simply...stupid. The reason the game world is flat is that it's simply easier, programmatically speaking, to represent it as such.
It would also be easier to provide a world without birds, trees, grass, and ponds. However, these were included in the game because the makers wanted to make a good representation of the Earth. If they wished to go into such deailed, Zelda's world in that game would have been spherical. It was not.
I know this is difficult to grasp. Try to focus...
Creating a spherical game world is unnecessary. Creating a virtual world on the scale of a planet wouldn't change the perspective for the player and would add nothing to the gaming environment.
Creating a virtual spherical world for a game would also consume a lot more memory, and the storage medium for these games does have a finite amount of space. Furthermore, the consoles themselves have a finite amount of system memory to run them.
Console games are not easily patched once they're out on the market. Because of this fact, the programming tends to be simpler.