Very nice post, DRvee.........certainly brought on a lively discussion. There is a place for lighter workouts. It can almost be like a steroid bridge in the midst of a lifetime of heavy drug use. You won't gain anything, but you won't lose much either if done right.
I train heavy and fast. One body part a day, all compound movements and the basic power lifting exercises, every set to failure and out of the gym in 45 min. Try this for 30 years, and a month of light training will do you good every now and then. I need time for my aches and pains to go away, and a break from the intensity.
And, I enjoy checkin out the ass, catching a steam or whirlpool....stuff you can't do in the middle of a serious assault on the iron. You got to relax sometimes, if you plan to lift forever.
Sometimes I like to leave the weight room and go over to the "fitness center", get all the equipment sweaty, and not have a towel to wipe it off with. It really pisses the pencil necks off.