I did it because it felt natural and because, as a single working mother, I would have otherwise been restricted to just a couple of hours of physical contact a day. Not nearly enough.
The classic lit on this is "The Family Bed."
Apparently, one of the advantages of sleeping with the kids is that they get sick less often and recover more quickly than kids who sleep alone. Another advantages is that the mother gets much more restful sleep because she does not have to worry about what is happening with the kid. She can just open her eyes and check.
Of course, one has to get more creative about where to have sex. But that's ok. Nothing wrong with creative sex.
Joanna