Good idea. Who will enforce it? Because those with the most to lose will always, by definition, have the most money to throw at un-separating them.
I am not implying that it cannot be done, but I like to encourage people to think long and hard about why things are the way they are and what systemic changes would be necessary when they propose that "society should do X". Most people would agree that we shouldn't have big companies running the government. So why do we keep letting them do it?