You keep bouncing back and forth between two arguments that are related but not identical.
Your argument that halflings should have more official support/inclusion I agree with 100%. I think there is plenty of room on the table to spread around the fiction amongst all the different groups and come up with interesting stories involving them all.
Your argument that halflings make for poor PCs or PHB fodder because of their lack of inclusion or because of some perceived (by you) gap in lore that makes them nonsensical I disagree with 100%. I have included halflings in my campaign and players have played halflings without any trouble.
I would like to see more lore for them (agree with you) but do not find the amount of lore they have by default at all a problem (disagree with you).
I do not have to have official adventures or appearances by halflings for my game because.....I don't use prepublished campaign settings or adventures at all. I do steal bits and pieces from different settings, such as the Faerun Pantheon and warforged from Ebberon, but even in those cases I use what is written as a base from which to create my worlds reality.
I (and many on this thread I suspect) don't view the different races lore as monolithic as you do. Saying halflings are happy farmers is a generality, not a baseline. This doesn't preclude halfling evil cultists, muggers, clergy, inventors, wizards, or anything else a thinking being could pursue. There might be a halfling village who figured out how to make electricity from a dam....if that's what the story calls for. They could be at war with a keep of halflings who have decided to make a halfling kingdom by force who are in league with dwarven druids living in the woods and artificer tinker elves who hate the outdoors but build awesome runic plate armor.