What advantages are these? All I can count is having a static, one-way tunnel to the same dream ending we typically have. This gets boring personally, but it's easier that way because new players and seasoned players alike can keep on a road to the game's end.
I actually don't know what you mean with that bolded sentence.
One advantage of linearity is the ability to tell a much more detailed and engaging story. Yeah, yeah 'Nontadnoo no care bout stoorey' but since
The Wind Waker, Zelda has put more focus on story, culminating in
Skyward Sword's narrative which has some people P'd-Off by how in focus it was. But if Nintendo are committed to developing stories then linearity is a better style than non-linearity in that respect.
Another advantage would be puzzle depth. If, when desiging Dungeon 6, the level designers
know you will have Items A, B, C, D and E then they can create puzzles and methods of movement that rely on all of them, devise ways to combine the use of multiple items. This can make later dungeons more challenging and more creative than earlier ones, something which we generally expect from video games. Sky Keep in
SS was based on all the previous dungeons (and some overworld areas) and yet didn't make any particularly impressive use of the range of items you are guaranteed to have by that point. A real wasted opportunity in my book.
Linearity can also make it easier for the game to teach us. We can learn certain skills, certain patterns or certain item uses at an appropriate time, rather than finding ourselves in a situation that we either can't handle or get stuck on. I'm quite big on games teaching us a few things that we can then apply later on in the game and some linearity, particularly towards the beginning, can help facilitate that quite nicely.
The key ingredient here is that these examples can all be applied to a game with some degree of non-linearity and, in fact, the first two can be found in
SS (unfortunately, rather than allow us to apply 'old tricks' to new scenarios,
SS recycles the exact same scenarios in later areas, case in point, Sky Keep).
SS is a very linear game and that makes it easier for Nintendo to tell their story and for dungeons to be designed with multiple items or abilities in mind. Then, we have the Song of the Hero Quest and we're free to go and do that in whatever order we choose. So, again, I think some non-linearity is a good thing, but I see absolutely no reason to remove linearity entirely.