For the smaller 4s packs like those used on the Movi, why isn't an overdischarge protection circuit or cut-out used. Other devices use them. I know the Movi quits working properly at low voltages but my question is, why isn't protection built into the battery?
MoVI will shut off at low voltage as you mention. And before it gets to that point generally the motors, when ask to deliver a load, may not have enough power to do something like a rapid movement. Really isn't an issue. When the battery lights get down to 2 begin thinking about a replacement. Down to 1 and replace.