From a practical point of view they made sense, you could put some of the electrical gubbins in there & in some there was room for gauges & in some Enfield's even little side-lights. Exposure to the British weather, could cause numerous electrical gremlins if you were not careful in your maintenance programme!
Belstaff, with pocketful of fuses & bulbs on a cold Winter's night, must bring back some memories...
Cheers
JBW