IMO baby must have: diapers, wipes, a place to sleep, a blanket to play on with a few small toys, car seat, tub and baby wash, and some clothes. As pp said, everything else is more convenience or specific to your baby's preference: stroller, pack and play, carrier/wrap, diaper bag, burp cloths, baby towels and wash cloths, bottles, pacifiers, etc.
Things I found wasteful: crib sets -we never used bumper or comforters; the high tech pack n play with all the bells and whistles -we only ever used the basic part and bassinet, the rest was a pain to lug around and travel with, swaddling blankets -both my kids hated being swaddled, baby towels -my kids preferred to be snuggled in regular bath towels and it kept them warmer and dried them quicker, with DD the swing was a waste of space, but with DS totally necessary if I needed to put him down to get anything done; we also didn't use our monitor for more than a week because our bedrooms are all close enough and I can hear the kids no problem. But as others have said, everyone is different with what is useful and not. GL