I would like to see what happens everywhere after Hyrule is saved, but it would create a problem with the boss. If you could save on a different file it would be kinda kool, but then you would have like two files taken up out of the traditional three that Zelda has always had.
And really, getting extra things wouldn't be too kool after you have already beaten everything. I mean sure not everyone gets everything in the game the first time through, but if you couldn't go back and beat the boss or get those things while in gameplay instead of after everything was over then they wouldnt be very useful.
Maybe if you could only go through and play after the credits, like save and have it save just before you beat the final boss like other Zelda's, but after the credits be able to roam around and check stuff out until you turn the game off. I would prefer that.