The issue, of course, is how you support multiple settings when there are finite resources (time, page count, etc) to do it. Elves (to use the go-to example) are present in every world and each world does something a little (or a lot) different with them. That makes it hard to inform a generic "elf" culture, society, religion, even appearance.So,o you get what 5e has done; elven information is a mile-wide and an inch deep. Contrast that to Pathfinder, who has developed elves as Golarion sees them, and you can use that information to inform design choices. (As a second good example, Golarion goblins undertook a radical shift from 1e to 2e, which was partially explained away in canon, something they could do since they only had to worry about Golarion. In D&D, the change to orcs from villain to hero is a confusing jumble of mismatched lore, retcons, and don't-think-about-it. If they only had to deal with one setting, they could move forward with a moment where orcs are elevated to the status of PC race (they overthrow Gruumsh, prove their valor fighting side-by-side against a demon, army, form the Kingdom of Many-Arrows 2, etc). But instead we're getting a "orcs are strong" sort of generic filler any if we're lucky they will explain how the changes to orcs work in the next Faerun or Oerth or whatever guide...