That sort of inclusion baked into a setting is pretty "modern" in feel, and aligns with a large amount of the play culture who have entered the hobby in the 5e era.
Kingdoms of Kalamar has that level of inclusion when it comes to species. It does include bigotry in the setting, but it makes it obvious that's a bad thing (it outright calls bigotry Evil) and DMs are free to remove it since none of it is load-bearing.
It was the 1990s so LGBTQ inclusion isn't really there, but it doesn't have any homophobic or transphobic tropes so a DM doesn't need to do anything other than add some LGBTQ NPCs to reach the same level of inclusion as Exandria.
1) Kingdoms of Kalamar is not a WotC product or available on DDB. That matters to a lot of people.
2) Whilst I have not read Kalamar, I assume that, given it's association with Greyhawk, it is retro, low magic and aims for gritty realism. Not bad things in themselves, but very different to Exandria. If you like one, you probably won't like the other, and visa versa.
3) It makes Flying Fox Man look like the most famous Superhero ever.
1. Yes, Exandria is the Starbucks of D&D in that it's way more available and heavily advertised. That doesn't make it the better product.
2. No, no, and no.
It's not near Eberron's level, but new technology and the combination of it and magic is one of the many things that has the setting on the tipping point. There's even at least one worker's revolt brewing.
It's high-fantasy, one of the higher-level adventure ideas given is stopping a cult from putting out the Sun.
I would guess that "gritty realism" and "There's a spell that drops bird poop on your enemies and the God of Undead rewards his followers based on their kill-counts and they thus aim to get a high score" are mutually-exclusive. The latter's even given as a reason why one of that god's followers would be fine working with an otherwise Good party since they're getting lots of opportunities to semi-legally practice their faith.
You shouldn't make assumptions.
3. Irrelevant, the point is the comparison between the two settings.
Exandria is great for younger players, those who don't want to deal with certain subjects, and those who are fans of Critical Role. Kingdoms of Kalamar is the better generic setting overall (in my opinion anyway) since it's fine for both younger and older players, capable of including or removing certain subjects if the players and DM are or aren't comfortable with them and you don't need to know anything outside the setting to fully appreciate it.
Actually Exandria might also be better if you want to play a Tiefling since Kingdoms of Kalamar was written back before they'd exploded in popularity as PCs. But it got a 4E update that added them so I might be wrong there since I haven't read it.