One potential pitfall, as I have mentioned before, is that most of the time we don't really have anything interesting to say. In order to maintain an exciting pace and indulge the protagonist's self-importance, even nobody non-player characters may respond with overly dramatic dialogue and emphatic intonation that seems out-of-place. Dialogue becomes even more treacherous when player choice is involved.

Intimate chats with friends and family is not unusual. These conversations can last quite a long while, covering a range of topics and including long rants. A good game of D&D can include such ramblings because the game creator is there to make up things on the fly, but videogames are sadly incapable of such spontaneity without exquisite AI. In the mean time, our own dialogue takes the form of text-based responses.

been?" with an accusatory tone. Hotel Dusk has no voice acting and suffers from this problem far too often. The detrimental solution is to create extreme dialogue that is difficult to misinterpret but obviously overblown.
Dialogue choices in Fallout 3 are clear cut, even extreme, seeming very unrealistic. Developing a morally gray character is difficult in these circumstances. When I threaten to kill someone, I have no doubt they'll understand my meaning. Such threats cannot be insinuated; thus, a great deal of narrative depth cannot be created without veering from the standard dialogue construction. Also, Fallout's protagonist repeats your text choice verbatim, without their own accompanying voice. In order to simplify player choices, the game unrealistically constrains dialogue.

Of course, these are my personal preferences. I can understand some players wish to know exactly what their character is going to say before they say it. But to satisfy my own desires, dialogue options should have as much information regarding its tone as necessary to convey meaning, including descriptive tags (such as hostile, inquisitive, insulting). Alternatively, voice work can accompany text choices to convey meaning through intonation.
Including realistic NPC relationships, there is still quite a bit of innovation to be made in RPG dialogue. We could always relegate all conversations to cut scenes, but we would be missing unique opportunities for interaction in moments with undoubtedly long lasting effects. Some great and terrible repercussions can stem from simple conversations. Alternatively, we can go the Zelda route and just not say a thing. Sometimes, shutting up can be awfully appealing.