currently there is only one solution: In dangerous areas, separate your group and move chars individually.
Yup. Unfortunately, when hazards are around, chain system is a liability.
On a side note, what I wouldn't give for BG1&2s "pause when trap is spotted" feature.
That's a good idea. In this case the equivalent would be automatically going into turn-based mode. That would force people to move characters individually, which as a couple people mentioned, is the best (though still incomplete) solution to these issues available in the game as it currently stands. (Well, not really
force, but it would make it the path of least resistance.) There's a couple places where it does this but not nearly enough.