"There are cantrips to create illumination" Yes, that cost concentration, meaning you will be gimped out of Hex, Witchbolt, or any difficult terrain utility, so to not be gimped in dark instances, non-elf spellcasters have to effectively gimp their damage, CC, and utility to be on ground with elf casters. And casting said cantrip already put you one spell behind a darkvision race in terms of output.
The Light cantrip doesn't (or at least, shouldn't) require concentration; importantly you can put it on another person and it lasts an hour. Thus it's still a very useful cantrip even if the caster has darkvision.
Although last I played (patch 3), casting Light on someone didn't work properly. Lit companions still saw even adjacent enemies as "Shrouded in Darkness" and thus got disadvantage to hit :\
