In the group of people I play with each player has his own way of developing his civ. We like our civs to be unique. Further, while we've never really liked the research sharing, it makes even less sense since we started playing FFH2. In FFH2 the civilizations tend to be much more differentiable with drastically different technological needs.
Alternatively we can set it up so we aren't team mates, merely at peace with one another, but it sure would be nice to share vision with each other, especially while we're waiting on each other to finish turns.
I have looked around the XMLs and Python for anything that might disable research sharing, but I can't really figure out how to get rid of it.