Whizbang Dustyboots
Gnometown Hero
That's not the motivation.Realized that WOTC really wants all the options, but again if everybody is special, nobody is.
They don't want to be in the business of saying "X percentage of blood from ethnic group Y makes you big and bestial." That's a PR disaster waiting to happen, especially if they accomplish anything like getting a LotR or MCU level mindshare with the public. (The public currently knows D&D is a thing, but not the details.)
If you thought the Twitter blow up about how orcs were depicted in the Monster Manual and Volo's was bad, wait until it's cable news going after D&D for half-races.