Is Eberron the only exception for the flaws pointed out by the OP?
In Eberron languages are cultural and have historic reasons for being used.
"In Eberron, languages reflect culture and geography; a dwarf raised in Breland might not know Dwarvish, but a halfling raised in the Mror Holds might...
This is what the Monster Manual has to say about alignment, specially the neutral one:
"The alignment specified in a monster’s stat block is a default suggestion of how to roleplay the monster, inspired by its traditional role in the game or real-world folklore. Change a monster’s alignment to...
The Secrets of Xen'drik book goes really depp into the continent. it's a 3.5 sourcebook that is available on DM's Guild.
https://www.dmsguild.com/product/51648/EBERRON-Secrets-of-XenDrik-35
I'm kind of late to the conversation, but the Lizardfolk in the MM are explicitly said to be the elemental variants of them. The humanoid Lizardfolk are nowhere to be found in the MM.
It's related mainly to this part:
"For a while now, Wizards has had a reputation for discouraging homebrew. As a big business, they prefer for you buy their options. "
This sounds very cynical to me, when they have their products for sale on Wizards channels...
WotC is a bad company, owned by a even worse company, not trying to defend them. But to me, if you need to put down another product to make yours look good, its because yours is not that great to begin with... And its hard for me to accept all this moral high ground that Kobold Press wants to be...
You know that Kobold Press is in partnered with WotC right? Their product is literally on sale on DnD Beyond. This all reads hipocritical to me, even mre so when they say DnD doesn't support homebrew, while selling Kobold Presses third party products on their website...
The main reason I think it's not too high is 5e's design. Fights against solo enemies tend to be really really easy in 5e, and most monsters have multi attack so this will be really good against one attack and useless against the rest, so it will end up being completelly fine.