Yeah that's a fair point. I wouldn't suggest having every character chip in to every conversation. I'd just suggest having them chip in where they've something unique to add to a situation.
In a situation where there ends up being lots of options, well that's ok imho. It's a benefit of a diverse party. If you're a party leader you're going to know what your team can do. In the middle of a conversation your mage might lean in and whisper a suggestion in your ear or you may turn to your fighters and say 'go beat it out of this guy'. Maybe a neat modification could be if there were multiple folks in your party with similar skills maybe instead of listing them all next to each character you could have them act together for a little boost to your roll. Like an intimidate act with three fighters in your part would be more effective than one.
Ultimately I would like to see what options are available to me without doing something 'gamey' like clicking all my characters or restarting conversations with different folks. If there are lots of options so be it, you can still only select one.