Splitshot hit it on the head, you can't really hurt the population by keeping a few fish, so it's up to whether or not a person uses what they keep versus wasting it. I don't eat a lot of fish so whatever I keep is usually given away to family or friends. If I ate more fish, I'd probably keep more fish. Like MP said, though, you pretty much gotta keep scams unless you can get 'em during a spell of cooler water and what not.
As for wild versus hatchery, I think Michigan anglers put too much faith in the wild fish philosophy that is so prevalent in Washington, British Columbia,etc. Face it, outside of a couple waterways (the PM and Little M, most notably) wild fish do not add up to a significant percentage of the steelhead population. Our hatchery fish come from wild stock, so genetically they're basically the off spring of wild fish albeit raised under ideal conditions. Are you adding to the population by releasing a wild fish? Probably not any more than if you were to release a hatchery fish. Does releasing a wild fish on the Grand somehow add to the fishery? Probably not since 80% of the fish that do successfully spawn will die before they get a chance to spawn a second time. The offspring of those fish? Most if not all will die once the summer water temps go up. Unless you have a stream where water temps remain ideal year round, the natural reproduction in steelhead will be insignificant at best. Taking a Swan Creek wild fish or a Dowagiac wild fish will not be noticed in the grand scheme of things since more than enough other fish (both hatchery and wild) will be there to go through the spawning ritual--a moot point since a great deal of the offspring will die once they reach the warm mainstream. Sure, catch and release is a good thing and I practice it most of the time, but if I get a loose hen and it's a wild fish (or happens to have all its fins)--I'm breaking out the ziploc and the stringer. I'd much rather feed those loose eggs to other steelhead instead of just letting them end up as Sucker and Carp food.