I'm preferring this sub race method over adding completely new races, honestly. It feels like we get more this way. Not to say I wouldn't like completely new races, just that if I had to choose one or the other it would probably be all these sub races.
It doesn't bother me one bit that some of them are just slightly different versions of existing races. I don't see it as lazy because it makes perfect sense and is something people have specifically requested for a long time, like dark iron dwarves.