I only wear boxers when I get out of the shower at home. I cant stand wearing them under clothing. Too much fabric. But at home it's nice to lounge in. I get boxers that have a button on the fly. That way I can unbutton them so I can "accidentally" fall out easier if friends or whoever are around.
Me too, I can't stand the extra material inside my jeans or slacks. If I have to piss, I'll unzip, unbutton and pull the waistband down to expose my cock. I'm retired, so I seldom have a shirt that tucks in.
I usually wear some boxer sized cotton shorts at home....All day unless I'm going out, and maybe to work in. I'm often commando, so I can just piss out the leg.
All of that is much easier to me than having an open fly. So I probably wouldn't use that.
But I can certainly understand the erotic imagery of having a big cock dangling out of an open fly. So I can't fault you guys for enjoying or displaying that suggestive concept.