But, half-elves don't have their own societies. They never have (not in core anyway). The specific write up in the 5e PHB is:
I have to ask, what uniquely half-elf mechanics are there? In 5e, a half elf gets:
Darkvision, Fey Ancestry and 2 skill proficiencies.
That's it. That's the sum total of the mechanical elements of a half elf in 5e. Darkvision, I hope we can agree, is not race defining. Fey ancestry? Sounds great, but, again, is entirely dependent on the DM to actually see any light in play. So, proficiencies? But, which proficiencies? After all, the 2 bonus are entirely up to the player, meaning that every half elf will have different ones.
Also, why can this only be done with one character? Huh? Why would this be a one off at all? Half-elf is a pretty popular option. I can't see why losing 2 proficiencies and gaining a cantrip would massively push people away from taking half elves. Because, at the end of the day, that's what we're talking about.
Trading 2 proficiencies for a cantrip. That is the total mechanical difference between the old version and the new. I'm really, really not seeing the issue here.