The power supplies are optional, not completely necessary, they're there for those that want to upgrade their system to get more from it.
As for the interconnects, Naim use 5 pin DIN connections due to their better grounding, among other reasons, and use them because they feel they sound better with their own equipment than phono connections. When you buy Naim equipment, you get the interconnects you need, so no extra cost there. Naim now include standard phono connections for those that want to use their equipment with other manufacturer's equipment. Mixing and matching isn't a problem anymore!!