The hardest part to see is that this device is not meant for us.
The average guy in these forums probably has a main rig at home the size of a small fridge... 10-14 bays and 1/2 a dozen fans.
I have 12 bays, and I'm using 7 myself, and want to leave the rest open for airflow.
OTOH, with an HTPC, there may be a total of 3 bays, used up with 1 DVD, 1 HDD, and 1 floppy or card reader... That extra PCI slot provides an alternative to using an external HDD. Think about it. Most HTPCs have more connectors on board for drives, than the case has bays.