As long as the goal is accomplished thats all that matters. If the goal wasn't accomplished then it would be poorly designed. If it ain't broke don't fix it. The only thing they could have added was upgrades to darkvision. Aka goggles of night upgrades.
Darkvision is a good design because 5e wasn't ment to be a 3.5 repeat. 5e explains just enough to get your imagination going. Then it let's you shine with your ingenuity.
Notice how in 5e it doesn't go into much detail about how darkvision works. Is it magic? Is it an evolutionary...
Hasn't been updated since 2007?! What? I got you.
I will be using actual physics to solve this problem.
1) How did you get darkvision?
A: Magic. This means a spell mostly.
B: Granted by a racial feature. This means the effect doesn't have to be magical. It can be a physical trait in your eyes...