But, let's say I want to try and make a Thayan, there's no reactivity to it, so there's no real flavour to the Human side of things.
I'd have thought something like that would be better handled by specifying a home location tag for your character, rather than by having a subrace? Of course, we don't know if the game is going to be able to handle any other home locations for most races other than Baldur's Gate, which at least at the beginning of EA seemed to be assumed to be the home of any non-Underdark races, but it would be great if we did have some other options. I just don't think introducing subraces for the different countries would be the best way to accomplish it.
Yes, the tag or the background system would have been perfect for it (and it was even suggested several times during EA).
But failing that, I see little harm in having subraces (cultures would be more appropriate actually) for humans. After all, a Rashemi would have very different skills/proficiencies and maybe even stats than a Chondathan, Iluskan or Shou.
And a cultural or homeland tag would have added much needed variety to the humans in general.
