The thing about the "35 races" to me is that sure, having 35 different cultures with interesting and deep stories, that are not just humans with hats is really tough. BUT if I was to DM a homebrew setting I would probabbly give my players a run down of the main races (those would have those rich developments) but still let them choose any official race, under the condition that for that we would have to talk and find the place of that race in the wolrd. That could be done in various ways:
- A small number of members of the race always existed but never formed a relevant society;
- Traveler/planar accident brought the character to a place were the race doesn't exist;
- Scientific experimentation;
- Whim of a god;
The list can go on almost for ever, but I'd say "you can chosse whatever you want, but not everything will have a great impact on the game wolrd, sometimes you are just one of a kind".