For me, I think it's mostly about personal preference. When I first started in photography, I shot nature and wildlife. Obviously, these are done outside and in natural light (good or bad). When I transitioned to portraits, I had adjusted to natural light and the settings I'd need in order to capture a subject nicely in it. I think my preference to shoot outdoors is also based on my preference, simply, to be outdoors rather than indoors. I prefer nature - I like being outside. I find great inspiration in being outside - It brings with it, a nice energy and vibe, which I feed off of.