Well said. I'm enjoying ToA too, but there is a lot of lore hinted at / implied in ToA, and to get at it you have to closely read between the lines and do your own research into products from past editions.
For example: the concept of "matumbe" (a forbidden magic involving possession/warlock-like pacts) was referenced in past products, actually plays a very significant role in ToA, but never is called out as such nor is it mentioned how the native cultures view it. Another example: how do the Chultan people view dreams in light of the presence of 3 night hags for the last century? Another example: how is Omu viewed by the peoples of Chult? Another example: where are the survivors of the Eshowe tribe or are there none, and what befell Eshowdow? Another example: have all the human tribes in the jungles gone extinct, or do some remain, and what are their cultures like?
If you compare ToA to another 5e module of similar length – Storm King's Thunder – in SKT there's about 4-and-a-half pages devoted to giant culture, King Hekaton's story, and the current giant leaders. I really think ToA is missing something like this for Chultan culture.
The intro to ToA is much more condensed...and generally, that's an aesthetic value I appreciate...to dive right into the adventure. However, when dealing a setting gamers are less familiar with than "bog standard pseudo-Western European fantasy" – and I'd argue a pseudo-pan-African inspired setting qualifies – then you really do need some pages devoted to that culture so the DM can give a verisimilitudinous presentation of the setting. With a bit of editing, I could easily see 3-4 pages on Chultan culture being included without changing the book's overall page count.