It is interesting how this topic gets so heated in fishing discussions. I've never heard it come up in any other sport. You never hear of 'trap and release' or 'shoot and release' in hunting. In fact, that'd probably be considered cruel unanimously.
If you are a fisherman, you've probably noticed that lakes often have limits that vary within the same state. These limits have been established to PROTECT the game in each body of water they are imposed on. So long as you abide by the law no harm should come to the sport. In fact, I will keep a fish if I know that it is damaged enough that it will not survive if released, even if it is not legal. Same thing when hunting, if a hen pheasant gets taken by mistake it will get kept. My view is that if I kill something, I use it. I do everything I can to make sure these mistakes don't happen, but by and large, they will from time to time.
These 6, 7, 8, 9+ lb fish already have their genetics in offspring. Old genetics aren't always better than new either.
I've more research to do yet on bass, but in hunting I do not worry about the game population. They say that hunters targeting quail and pheasant do not harm the game population because the majority of game you take would die in winter conditions naturally. I'm a fairly humble person, and so I think that whatever game you manage to take is likely the stupid game. People may be pulling 10 lb stupid bass out of a lake but the 10 lb smart bass are still down there .
There is some discussion about man vs. nature going on here. Any definition of nature that doesn't include humanity is flawed. We are a natural part of nature. There is no such thing as 'man vs. nature.' Humans, like any other living thing, require resources for survival. Our job isn't to refrain from harvesting resources, it's to do it in a sustainable manner.
That's my two cents. Just have fun fishing and respect your environment.