It is largely subjective, but I hold my stance that there is a part of it that is subjective. I couldn't care less about 90% of Elven, Dwarven, Gnomish, Halfling, Orcish, Goblinoid, and other racial deities (which is why I support settings that have less deities, like Theros and my homebrew world, and also like Exandria's use of a slightly expanded Dawn War Pantheon), and I can say for a fact that the average D&D player cannot tell you the name of the Halfling god of agriculture or who the god of air from the Forgotten Realms is. Those all fit into the "filler lore" category, because they don't add anything to the game besides just more lore-baggage that the FR has to carry around with it.
If halflings have to be a core race in D&D, they should earn their place with having as good lore as the other races. Elven reincarnation is lore that inspires character concepts, as does the Duergar-Dwarf conflict, as do many other parts of the lore for those races that without, they'd be on about the same ground as halflings. Frankly, even the Gith have more inspiring lore than Halflings, and I don't want them to become a main D&D race because they're fairly niche and are supposed to be (both by appearance, mechanics (psionics), and where they live; Limbo and the Astral Plane).
Halflings should have something drawing for players and DMs to be inspired from. If a player can read the Dwarf-Duergar Conflict lore and say, "Ooh! That would be cool to create a PC around!" there should be something similar for Halflings' cultural lore. I gave examples in my previous post for possible halfling cultures that could do this (by them being enforcers of happiness, or a culture of people that forces their practices of happiness on others), and I gave other examples earlier in the thread, too (with halflings that are gluttons and pleasure-addicts). It doesn't even have to be any of those specific examples, it just has to be a drawing culture concept that inspires character ideas. The current "pastoral farmers that do nothing but farm and occasionally send nobodies to become heroes" is obviously fine, but it's not comparable in this quality to the lore of Dwarves, Elves, and lots of other official races/cultures in D&D.