It's like a center diff in an awd vehicle- you want every option available to you, not just low range.
What if you shut your bike off at dusk/almost dark to let some hikers walk by... the lights might be nice.
What if you wanted to idle outside work at night while you ran back in to get your phone... No lights might be nice.
And sure, high speed getaways under cover of darkness is always a plus!
what if you dropped your headlamp over by your tent- yeah a quick light from the bike is fast& easy, but no need to wake the camp