If you can read the PHB descriptions for humans and halflings and not recognize that there are significant differences in the way their cultures are represented, I'm not sure what else to say about it.
The Halfling liking home and safety, is an insufficient distinction from the Human.
If halflings and humans are the same except for stature, why are there no halfling cities, or kingdoms, or armies, or politics? Why do you think that this obvious difference is not a difference?
There are Halfling communities, such as nomadic communities, ... just like there are Human nomadic communities.
I think I don't understand what you feel the qualifying bar is for "different enough" from human to be OK, especially in the context of the PHB.
Heh, what I WANT is more design space for each lineage, so that the mechanics of the nonhuman lineages can be powerfully different from the Human. I didnt have this kind of problem in 4e because there was enough design space.
(I am actually ok with the Custom Lineage design space, if I homebrew the feat to focus on the salient distinctions. But the official restriction to only the current feats and qualified feats remains insufficent. Indeed, it is almost identical to the Feat Human.)
In the context of the Players Handbook, I want the Halfling to mention unambiguous nonhuman lore. Laser beam eyes? Heh, I dont care. Something. Anything!
Anything that is obviously not a Human.
Heh, to say that a short Human is a separate species, is almost an insult to reallife short people.
You really don't think a race that utterly lacks the drive to get and wield power isn't sufficiently different from humans?
Correct, the Halfling liking home and safety, is an insufficient distinction from the Human.
I dont mind the trope that Halfling lacks ambition to an unusual degree, if and only if, it is part of a larger package of traits and lore that are clearly nonhuman.