Although there was no technical reason that the old chargers had to have a moulded-on DC cable. In fact it may have been better from a usability and durability

Although there was no technical reason that the old chargers had to have a moulded-on DC cable. In fact it may have been better from a usability and durability perspective if the DC cable had had a Magsafe connector at each end, one for the PSU and one for the laptop. And with that design they wouldn't have needed to introduce a new charger at all..