Hmm...there are actually some worldbuilding considerations there. If humans get -3 attributes and are now the same as other races, then the rationale that humans might lack cool extras but are more versatile is actually bogus. Unless they get, say, additional skill or proficiency slots that can be freely chosen (otherwise where would the versatility be) between categories. And not just one, because every attribute affects several skills, typically 4. Any one -2 to an attribute reduces the attribute bonus and thus typically rolls for 4 associated skills by one. Which means that a -2 is worth two skill slots. In practice, the effect might be a little less since you don't usually roll for all of an attributes associated skills in a party of 4, but still I'd say the human -3, if that's kept, is worth two additional, freely selectable proficiency or skill slots.
However, if I played a human, I'd still prefer to have +1 on every attribute.
