The paraphrasing and spoken dialogue allow for a stronger flow of emotion during dialogue sequences. The way Dragon Age: Origins was set up, there were a lot of cuts of characters emoting in rapidly different ways, depending on your unspoken response, that it all felt a bit artificial.
This seemed to have been solved by giving the character a voice. In doing so, the interactions between the hero and other characters are able to cause sound transitions within the dialogue sequence. I can assume there’s still going to be the sharp change of character when ‘investigating’ characters on different topics, and once in a while you’re going to hit that one dialogue option that’s preset to have them snap at you—even though you and whoever just shared some friendly water cooler rumors—but that’s just a inherent issue with the system that nobody really cares enough about to have an issue with.
In response of the characters appearing to be more genuine, your own character comes to life. Because you’ve felt that transition between your spoken response and that change in character, it’s more obvious of who the both of you are. Dialogue within any story is the most supreme tool of binding the viewer, player, or reader to the characters—capable of very simply integrating personality, history, the conflict of conscious and subconscious, emotion, and bias, it supersedes voiceless interaction by a mile (something DA:O also missed, but that’s pretty damn irrelevant in more ways than one).
After skimming through this thread, I can see people were keen on the idea of paraphrasing so long as it fit tightly with whatever the corresponding dialogue ended up being. Now, when I played through the first Mass Effect I was kind of ticked to realize some of Shepard’s responses didn’t match the few bit of words that paraphrased them, but by the time I went back and replayed it to get a new save for the upcoming sequel, I realized I must have been pretty damn selfish. Sure my character didn’t say what I wanted, but he said what he said so the characters could properly react to what I wanted—yeah, I know that sounds convoluted, deal with it—in the end, what it did was carve out the personality of the commander (If this is what he wants, this is how he’s got to play the game).
You have to realize that Hawke isn’t going to be your character. Just as DA:O was, DA2 has a predetermined story with predetermined themes and, more importantly, a predefined main character. He has a history and a future that, sorry, you don’t exactly have a god’s freedom in choosing. People are going to develop him in certain, differentiating ways, but they are all going to learn about him and his story. I believe paraphrased dialogue is a great way of doing this. Even better, icings such as ‘aggression’ or ‘flirtation’ affect much more specifically the ways you’d like to see the characters mature.
The way I see it, the only downside to voicing the main character would be if the voice actor behind him was bad. Or Gilbert Gottfried.