I could NEVER let my children sleep in bed with us. I would be up all night afraid I had rolled on them or kicked them out of bed. Also when you spend your entire day with them, there is nothing better than putting them in THEIR bed at 8 oclock and having the rest of the evening to your self.
I can't think of ONE good reason why they SHOULD be in your bed
I think parents that do this, do it for themselves. Maybe because it is easier