But it's a hekuva lot more interesting than a stat boost.
That's possibly true, but it's a hekuva lot less likely and obvious than stat differences. It's fairly easy to justify most stat differences from physical differences in the species in question. Is it heavily built, or slender? Is it tall or short?
It would be really odd if there were no stat differences at all between 3' tall 30lb humanoids and 7' tall 300lb humanoids.
Indeed, even your suggestion while it does suggest flavor (the race is 'magical') is highly unlikely from the flavor you gave it. Which is more likely, "Due to the High Elf thirst for knowledge, they all start play with +1 intelligence." or "Due to the High Elf thirst for knowledge, they all start play knowing 1 cantrip." One suggests a very broad based inquisitiveness that manifests in knowing more stuff, regardless of the stuff we are talking about, and the other suggests that every elf in their background has been exposed to the same stuff (that is, every elf, regardless of background at some point encounters magical knowledge). And which is more likely to make one want to play an elf?
I'm not at all saying you can't do things with racial abilities, or even that it is wrong, but I do think that it is more intrusive that stat adjustments. There is a trade off between doing things that are highly flavorable and thereby imposing flavor on the campaign for anyone that wants to use the content, and doing things that are less flavorable but thereby leaving much to the interpretation of the individual campaign. I would imagine that most campaigns that care about questions of nature vs. nurture have already got some ideas about how to fill in the holes and where a races usual attributes come from, and really don't want the mechanics or flavor of the edition du jour to change what is already settled lore within the campaign. Speaking from experience, it feels like having someone try to force their house rules down your throat when you have major changes in lore or the mechanical correspondence to the lore.
Or in short, elves might already be too established of a thing to meddle with much.
But, ok, sell me on the idea. Establish some ideas for races that have racial features that are mechanically interesting and evocative and don't involve attribute differences, and then show me that this avoids the concern over "racial essentialism". For example, is getting a bonus cantrip more of a big deal if you are a spell-caster, or more of a big deal if you are not, and in that case does it push the race toward one sort of class choice or the other?
