Mystra explicitly favors humans though.
From her lovers and chosen being almost entirely human, I think there was about one half elf chosen, to the sorcerer daughters she chose to birth being humans as well.
No matter how you slice it humans not being able to get +2 in in int or cha is just doesn't fit with the lore.
Take another example, Drow, known mainly for their evil clerics/evil church can't get even a measly +1 wiz. Not to mention Drizzt one of the most popular characters of the franchise, a range, can't get his +1 wis either.
The old asi are a gamey relic of the past. Limiting character builds and ideas in a game where character builds and ideas are the main focus is silly.
Mystra is bored out of her skull and human craziness is fun to behold. No matter what happens, they improvise, they adapt, and they overcome. And they do so without losing their potential in any particular discipline.
Humans not getting +2 in any stat fits perfectly, because the average human is not that special, and even the special humans aren't usually born as special Mary Sues, they have to take a bumpy path to get there. That's what the stat bonus shows, the beginning of the journey rather than the end of it.
That said, I'm not at all convinced that 5E does a particularly good job at representing the diversity of life in D&D. But making everything more generic is not an improvement, IMO.
