>Why are these even needing to be settable things at all??????????????

You need some way to disable disconnect to use certain broken SCSI
devices.  Also, the Emulex+NCR core `esp' device found in SPARC
chipsets has quite a collection of bugs, most of which crop up
only when using synchronous mode and/or reselection and/or `fast'
mode.  Each rev has a different bug-set, so having a way to avoid
triggering the hardware bugs is useful, in case the chipset *you*
have has a bug that has not yet been seen and worked around.

Chris