I've noticed that too. While I think it may be convenient to switch weapons in combat, I doubt it will ever be a gamebreaker that you can't one-click-switch....I'd think that a character has one go-to weapon and skills that support its use, and that an actual advantage in switching will be a rarity.

Also, if we attempt to keep combat closer to realistic, how quickly can one take a weapon out of a bag, stow the other one safely, whilst maintaining a combat stance? The minor delay of drag-and-drop switching seems an acceptable tradeoff :)

What you say does make sense. Dragging it makes sense for a decent switch-time!