Fair enough, but then I can think of an even better place to put the icon: the control center that is a single swipe away from any screen in the OS. This is all moot in newer iPhones tho, as the physical camera button in the lower right is the easiest and fastest way to get to the camera.

Anyhow, this is all just personal preference, of course. Anyone is free to put a camera icon anywhere they please. I just personally can’t stand clutter in my home or lock screens, so I tend to keep the number of apps there to a minimum and access everything else either via Spotlight or Control Center widgets.