The only potential nerf was shield dwarf. But even then it's too early to call a nerf.
Humans got a strait buff with the +2 main stat and proficiency an extra +1 in dump stats doesn't matter.
Similar story with half elves they lose 1 point in con or dex, not a big deal, and the light armor profincy for full casters is great.
I disagree with you on the half-elf. If it were medium armor, then sure it would be a step up, but you'd need a +2 light armor to match a single spell slot, and a +3 to beat it. The difference in dex is also a +1AC, which is the same benefit as the only light armor that is readily available.
We need to know more on itemization, but in a game with scripted magic items, more armor proficiency is almost certainly a good thing.
There was maybe 1 13 AC light armor in the underdark that had no other redeeming qualities. It was better to have quality robes and mage armor up. If your point is that it is good that after 20+ hours into the game you may start finding things that make your profeciencies useful, then you win your point. I don't think that is an appropriate amount of time though.
There are a handful of helmets and other bits and bobs that are better than an empty slot, but they aren't built to be caster friendly.
The shield is a better bonus than light armor, and it is good to have for casters since they don't need a free hand to cast spells. It would have been nice if there was a finesse weapon or two to go with it rather than armor that only 2 classes don't have access to (both of which have a better option from a level 1 spell).
