I wouldn't say unwise as Michael said. Well it certainly could be with babies - there have been instances of adults smothering babies not noticing whilst they were sleeping.

There is also a strong theory that sleeping next to your baby NOT necessarily in the same bed mind, can help prevent "cot death". Some medics think the sound of another breathing next to the baby, can prevent the baby "forgetting" to breath.
Some think it's a throwback to old times (caveman times?) when the tribe would of course all sleep together.

Sleeping with your children, well that I guess is a cultural thing. Can't see any harm in it, and it's company in the night for the kids, and the adults know the kids are safe with them.

Personally I wouldn't like it, I am too fond of my own space really Maybe that's cultural though - we all think we should have our own rooms