chmouel, may be you can give some insight as to why it has been disabled in mdk.
if you boot system with hot-pluggable device already connected it won't be initialized. (try to boot with USB flash without extra scsi). this requires hotplug rc script somewhere on boot. I guess it could be enabled for USB at least (PCI is another question), this would also decrease complecity of current /etc/init.d/usb significantly - amounting to just loading of HCI modules and leaving the rest for hotplug.
