If your flashlight use dictates changing batteries daily, it's a nuisance to unthread and rethread the tailcap each time. Why don't we have tailcaps that work like a prescription bottle cap? Push in > turn 1/4 turn > pop off tailcap. I'm sure there are waterproofing or other engineering problems to deal with, but surely they could be overcome. Easy-off tailcaps for frequent users would sure be convenient.