A good deal of satisfaction for me is observing the interaction between fish and their environment. Bare tank = no environment to interact with. Try breeding fish in a bare tank. It rarely happens and if it does, it's a testimonial to how much deprivation fish will tolerate. Behaviorially speaking, a fish in a bare tank has nothing but its owner to react to. How much time are you willing to put in entertaining your fish? It's absolutely amazing how normal fish behavior is enhanced and promoted by a stimulating environment, which may be nothing more than a substrate, driftwood, rocks, and plants. And they don't need a fully natural setting like "in the wild" to bring out the fishes' best behaviors. For fish, a little goes a long way. But they need something more than water, heat and food. I believe that a fish in a bare tank is experiencing sensory deprivation. Not that I don't put fish in bare tanks. When treating a sick fish, or quarantining I do, but in that case, you need to control the conditions. And hopefully it is for the short term. I think for humans, four bare walls is called a jail cell.