I think (and I'm probably reopening a can of worms wit this
); that Fi is one if not the only the character in this game that could've benefited from voice-acting and a few would've probably enjoyed her more that way.
Fi, during the entire game reminded me of a toned-down, less obsessed with killing Glados (from Portal/Portal 2). From the fact that she was just an artificial intelligence that accompanies Link through his journey, to the gibberish voice that sounded similar to Glados auto-tuned voice in the games.
Fi, was this AI that didn't understand Link's motivation to look for Zelda. To her, Link was just this human that she was supposed to guide and make sure he kept focused on "his quest". So, she was supposed to sound sarcastic or make feel Link dumb (at first) and also by constantly stating the obvious. You can even see this the few times you're given multiple choices to answer something to her and the way she replies back.
Look at many posts on this forum, were people don't get the sarcasm of others or get pissed off at the way some think and reply back with "do I need to write 'in my opinion' every time?". There are emotions (or lack of them) that are lost in written text, even more when the character's supposed to be an emotion-less artificial intelligence guiding someone through a new world...
.
I still really liked Fi, and don't mind voice-acting in the game; but still wonder if that would've at least made a difference in this case. Same way that Glados sometimes pops around in the game to explain things you already know, but since she sounds sarcastic and is part of her character; one just laughs and continues playing. To many, it would've been "more acceptable" if after hearing someone saying "Link go to the forest and get this"..and have Fi appear in auto-tuned voice saying "Master, there's a 95% probability that if you go to the forest, you'll find that". Instead of just reading it; since many feel as if they're just reading the same thing..twice.
Or maybe it was just Nintendo's plan to "state the obvious" as I mentioned earlier, for the people that spam A or the people that don't read/care about the story bits.
Who knows.