Because a 5.25 slot is not a dedicated optical drive bay. Some may want to use it for a fan controller or card reader. With a 5.25 slot an adapter can be used to fit a slim optical drive and a 3.5 card reader.Why not slim optical drive?
So the author nor Velocity Micro have heard of Silverstone's 450W and 600W Gold-rated SFX power supplies then? Y'know the ones that deliver more than enough power for a single GPU system without the unnecessary size of a full ATX unit.The case can also handle a full-sized internal ATX 80Plus power supply, meaning customers won't have to deal with an annoying power brick.