I agree with giving Dragonborn Darkvision. They're the only Draconic beings that don't have it, which makes it feel like a weird omission. Their race is also generally underpowered in the PHB and could use a small boost.
To solve the Darkvision problem I'd just remove Darkvision from elves and half-elves. Maybe half-orcs too. The low-light vision was just seeing decently well in environments with... Well, low light. I dunno who decided it should translate to total night vision. Only underground races and certain monster races should be able to see in complete darkness.
