I personally don't agree, with DN all downloads are in some sort of queue, either the the main queue or a secondary queue, it doesn't matter, they are still in a queue.
The main queue is normally always running, unless you want to stop all downloads in that queue so you just stop the queue (no need to stop all downloads individually).
If you want to pause/stop one download you just hit the pause button and it will stop, allowing other downloads that are queued to continue in it's place.. or if you want to stop all downloads or all downloads in a specific queue then you stop that queue / all queues.
From the sounds of it you are asking for a download to be detached from all queues so that starting / stopping a/all queues will not effect that queue, only pausing that specific queue will stop it. But I really can't think of any reason why you would want to lose the functionality of being able to stop the entire queue with a single click?
If this does not meet your needs for some reason please explain the situation and I'll see what I can do.