Man, this sure is annoying. You're shooting something with your bow. You press your hotkey to switch to melee or whatever. But whoosh, another shot has to go off first, because it's in the queue. Now does it switch weapons? No! That keystroke was lost. Now when you attack, what do you get? ANOTHER bow shot and probably yet another one in the queue! It's not just bows that are affected--it's just easier to explain using that example, and everyone's probably faced it.
I think I understand why this "swing buffer" is in the game. You don't want us to have to time swings precisely or have delays in our attack sequence. But this problem has a simple solution: when someone switches weapons (or perhaps activates any hotbar command)--just kill the swing buffer! Lose that "next queued attack," finish the CURRENT animation only, then execute the command.
DDO offers an active style of combat that is very appealing. But this swing buffer thing is a great nuisance that hurts that style of play.