You're not supposed to know how people are going to react to what you say. And I don't see how knowing the tone is at all helpful in predicting NPC responses.
I don't think you really understand my point. I'm not saying that I want to be able to predict how the character responds to my lines. But the thing is, usually when that sort of thing happens, it's not a case of "The Warden is trying to be friendly, but Leliana thinks they're being flirty." (Or "The Warden means to be sarcastic but Alistair is sensitive about the subject" or anything else along those lines). It's "The line is written so that the Warden is meaning to be flirty, Leliana naturally picks up on that and responds in kind, but the PLAYER thought it was only mean to be friendly."
Not having voice acting hides better that you're misunderstanding the lines, because you can just assume your Warden "didn't mean it that way" but sometimes I've found it pretty clear that the character is responding to a CLEAR tone that the Warden had--a tone that's not always obvious just by reading the line alone to the player.
As an aside to other points of the conversations, I think paraphrases can be done without being too confusing and I'm hoping they've figured this out in Inquisition. For an example of games with paraphrased dialogue that really easily conveys what you're going to pick, I'd point to Telltale's recent games like The Walking Dead and The Wolf Among Us. Here's an example. Sometimes it's the full line (or the beginning of the line), sometimes it's a paraphrase, and there's even times where the choice represents what the character is thinking and WANTS to say, but can't either because they get interrupted or because they know they're not in a position to say it. For example, this scene. I think the player here chose the silent option, but you get the same result if you choose to curse the cop out, instead.
Now, of course, I'm not saying Bioware should just copy Telltale's system. For one, Telltale's characters are usually more established characters in their own right than just a player's avatar to roleplay, so you'd have to change it to allow for more player agency. But I think that Telltale's system proves a few misconceptions about the dialogue in these sorts of games wrong that can be helpful when writing the games.
For one thing, it shows that you can be more redundant with the words on the screen and the voiced dialogue. It's the strong voice acting and direction in their games that carries the line, even though it's often partially or completely the choice you just made. Bioware has a similar pool of talented directors and actors, so I'm pretty confident they could pull it off. I'm glad to hear they're not being as concerned about repeating words in Inquisition, but I think they could take it even further and have the paraphrase be an outright shortened version of the line, or the beginning of a line.
For another, I think it shows that maybe the best way to look at the paraphrases is to think of them as what the character is thinking right in that moment, and the spoken line is them articulating it--sometimes verbatim, sometimes more eloquently once they've had a moment to figure out how best to say it. So it doesn't have to be "these lines would sound natural spoken out loud together."
That being said, I'm not saying that Telltale always avoids confusion. Recently there was the infamous "[Glass him]" paraphrase--a lot of people somehow thought that meant "be nice and pour him a drink" but what it actually did was have the main character smash a drinking glass over his head. If The Wolf Among Us had a tone icon--like, say, the crossed swords--it probably would've been MUCH more clearer what that actually meant.
So to sum up--paraphrasing isn't necessarily bad. And the tone icons are definitely useful. The main problem is just making sure that two things are communicated clearly somehow in the game--what the paraphrases actually mean (which can be accomplished by using short, clear phrases taken from the line itself or that are clear gut reactions ("I'm hungry" isn't a bad example in DA2 I guess?)), and that the icons are only indicating the PC's tone and not necesarrily the outcome (which could probably be shown clearly early on in the game by making sure that there's some examples of NPCs either misunderstanding or reacting poorly to any of the tones--even the diplomatic one, if they feel they're just using false flattery or not proposing a good solution).
Luckily based on what the staff is saying I think they already have been thinking about most of this, so I'm honestly not too worried.