I don't think there is any kind of design limit on conversations that there can only be two options. Most of the time that may be sufficient, but previous Divinity games have had multiple conversation options, including 'I'm not sure' or 'there are some things I need to do first' before accepting / continuing a quest.
Larian has already mentioned there will be things that people mention that you can follow up on, or not, but which are not presented as a quest. Maybe we can find the family of the guy that jumped off the cliff, or maybe not; hopefully we can at least notify the nearest town guards.
You do realize that going from about 2 choices to 5-7 triples the amount of dialog, and doubles the number of outcomes (assuming some of the different conversation branches end up in the same place). Adding more choices without meaningful consequences would be worse than limited choices; the extra work would certainly be worth it in some cases, but if your characters see someone drop their coin purse in the game, two options would be good enough, and three plenty.
Welcome to the forum.
