Although I haven't read though the entire thread but a lot of it.....many machines have for years had what they call the "low bobbin indicator". This obviously is different on various machines. Pfaff's have ared blinking light and you can get more sewing done even while it is blinking...as it does not stop the machine from sewing. After using your particular machine for awhile you just learn how much more you can sew before your bobbin is empty.
That said, a beeping noise would drive me crazy.