Of course I know that it's because you can actually choose his name but I think they could've totally handle it better, like this:
Make two VA versions of every line his name appears in. If yo simply choose the default Tidus, then they would actually call him that way in the game and if you gave him your own name, the lines would be the same way they are now.
I mean there aren't even that many lines where they actually address him so it wouldn't really take much more time or money and it wouldn't be hard on programming either.
So how do you think they should've handled this?