i am surprised that families don't have more votes.....
i have found that coding a project of any size is a major pain in the rear with out them
you need families for reusable code which is essential to medium to large projects.
behaviors can be easily be replicated with events (most of them anyway)
families cannot be replicated however.
not to mention you can use families to easily replicate the more complex behaviors as well as a lot of other features
besides families, we need animations!(for obvious reasons)