IMO the rise in attachment parenting methods stems from the high rate of mothers working full-time outside the home, feeling guilty about being away from their children all day and "missing out" on developmental milestones, or feeling guilty about a minimum wage daycare worker spending more waking hours with their children than they do, and trying to 'make up' for this lost time with co-sleeping and other attachment methods.
I view this parenting style as a sort of pathological paternalism, it's presented as being in the child's best interest, when in reality it's a psychological need of (usually) the mother. Babies need lots and lots of high-quality, restful sleep, and the families that seem to be dealing with serious sleep deprivation issues for both parent and baby are usually in the attachment camp.