you are missing the indisputable convenience of never worrying
if your battery has enough power left to get you home..
or the charge-cycle life of the battery going past taking a new charge

there is a handlebar mounted light wired to the hub,
that un plugs at the hub and comes off at the bars.
so can be taken off the bike.. quickly.
planet bike [LED], or Shimano, (halogen-bulb), offer them.