Well, just a short comment from me now. I think most of what you said could be a part of the reason. But I also thought of something else, and that's what I thought of as the first, that simply Hobbits were so much of a rural simple folk, that they just had to have something "intellectually deep" to spend their time with. I am pretty sure they usually did not delve into complicated philosophical disputations, we know they did not construct complicated technological inventions, but let's face it, they must have had some "intellectual needs" and they must have ventilated them in some way. So they picked the genealogies. As good topic as any.
