PrRC's Longsword as a +3 weapon is 'because' of this KotS dragonborn, so unfortunately it is a somewhat circular argument. It was suggested to me in the PrRC thread that all defenders have +1 attack, but that makes some weapons, like the javelin, a +1 weapon, which seems low to me.
The halfling's +1 reflex racial bonus is missing from the KotS rogue, OR the Paladin is missing +1 reflex from class and the halfling doesn't get a reflex race bonus at all, OR Corrin had an error, OR something is working in the background that we don't know about (seeming more likely the closer we get to launch date). Each new data point creates more confusion, not clarity, in some cases. Gah these books can't get here soon enough!
The reasoning behind the halfling's bonus to reflex was from Corrin, the halfling paladin. He has +1 bonus to each of his defenses. Originally, it was thought that all three were coming from his Paladin class, but as more information was revealed a pattern formed, where each class either granted a +2 to one save or +1 to two saves, and the Paladin was the 'odd man out'. Also, it seems that the Eladrin was getting a +1 Will (instead of the ranger providing +1 to all defenses once the ranger page was revealed), and the humans were getting racial bonuses to defenses, so there was precidence for race granting defense bonuses. It was suggested by several people that +1 from the Paladin to reflex was less likely then +1 reflex from the halfling, and so the change was made in PrRC in more recent versions. It is speculative still.