I don't think being lined or lineless affects the over all quality. It depends on the execution. Personally, I rarely see lineless backgrounds in comics so it evokes a sense of novelty to me when I see one. But even if you'll be sacrificing quality, sometimes it's worth it for the sake of practicality. There has to be some balance. It's a value judgement that totally depends on you
My style leans towards lined backgrounds just because it is easier and faster for me to do consistently. I don't think I can even do lineless backgrounds well enough