The Sword Coast Adventurer's Guide says:
Some half-elves in Faerûn have a racial trait in place of the Skill Versatility trait. If your DM allows it, your half-elf character can forgo Skill Versatility and instead take the elf trait Keen Senses or a trait based on your elf parentage:
Emphasis mine. The traits based on parentage are things like swim speed for aquatic elves or magic for drow parents. But here's the thing. Skill Versatility is
You gain proficiency in two skills of your choice.
while Keen Senses is
You have proficiency in the Perception skill.
Why would one ever pick Keen Senses over Skill Versatility (with Perception and another skill)? Is this a design oversight, or a typo where it's meant to be "and", or is there something about these traits that I'm missing?