Yes. Of the six places where I’ve lived, only two of those have had the bed with both sides open. In the rest, having it against the wall gave me more space for my desk (or just to even fit the bed in the room).
Yup. My bed’s in a just-bigger-than-bed sized nook in my attic-bedroom, and has wall on three sides. I have to crawl in from the foot 
Sleeping is one of those things I’ve just never been terribly good at. I get up in the night to use the bathroom, or check on the child, or do the dishes, on a regular basis. If my partner is a really hard sleeper I have no problem with just climbing over, but I think most people would be driven to distraction if I were forced to climb in and out over them.
Of course, there is also the option to exit at the foot of the bed, which is fine with me as well.
Protection-wise, I’m the lightest sleeper by far than anyone I’ve ever shared with, and wake more quickly. Even with a loud noise that woke us at the same time I’d be capable of reasoned response well before most people.
I said all that so I could say this: I’d find the wall side far more comfortable as I like to lean my back against it, but it just makes far more sense for me to take the open side.
I sleep on the right side regardless.
I don’t care. Probably from being in army beds against a wall for years, it doesn’t bother me. However, last couple of years I tend to have to get up once during the night so the outside would probably be better. Not an issue now. We have a king in the middle of the room.
Same here, wall or no wall. In fact, any future partner had better be content with the left side because this is non-negotiable. I’m single now, but any future partner had better be content with the left side or I don’t really see how it will last, no matter how much I like them.
Wall if occured. No need to worry about climbing over … slide down and get out foot side. (Waking my wife up is always a mistake.)
I have a slight preference for the wall side. It’s mostly because I’ve had experiences being rolled out of bed. It’s far less comfortable than just being squished a bit against the wall. And, yes, of course you get out of bed at the foot in that situation.
I voted with what I now see is the majority - “Doesn’t apply (isn’t against the wall OR sleep alone), but I’d pick “open” side if it applied.”
My wife and I sleep in the same bed, which sticks out into our bedroom - we both have an “open” side. I’d give her first pick, if one of the sides was up against the wall, but since I’m a night owl and am usually the last to come to bed, it would only make sense for me to have the open side, so that I didn’t have to wake her every time I climbed in.
Open side, because I’m an early riser; every woman I’ve slept with more than just a few times, I’ve consistently been the first one up in the morning. No point in having to crawl over her and wake her up, too.