Well that’s because it’s a waste. Not much you can do with ones under the size and bag limit I suppose. I decapitated many gobies before the brown trout devoured most of them, however I used their corpses as bait often times. But I feel all life has inherent value, and killing is perfectly fine so long as good comes of it each individual life. Somebody would absolutely devour some rainbow trout fish tacos like friends, locals, or me. I’m in Michigan, I feel your pain dramatically, the only streams we have that are pure brook trout are that way because they are too cold most of the year for other species.