#1 - The type of carry should be left to the judgement of the gun owner, not the gov't and especially not to people whose lives are not impacted by someone else's decision. "Pro-choice" should apply to everything, not just killing your own fetus.
#2 - Open carry has the OBVIOUS benefit of making drawing easier and faster. Concealed carry requires clothing over the firearm, oftentimes tucked into the pants. Practice improves speed, but nothing compares to having an unobstructed path to the weapon. Don't agree? USPSA matches and handgun training schools don't allow IWB concealed carry holsters for OBVIOUS reasons.
#3 - Another OBVIOUS benefit to open carry is the concern by Cops that they can't tell if you're armed if you're concealing a firearm. If I were a Cop, I'd be less apprehensive of a displayed & holstered firearm than the potential risk that someone I'm interacting with might be armed without my knowing. Some states require notification you're armed whenever LE makes contact with you. From a safety perspective, both yours and the officers', I think transparency (OC & notification of CC) helps LE see you as a law abiding, armed citizen and not someone to fear.
#4 - You can "what about" over what some criminal might do all day, but fact is: if someone is looking for a victim, they routinely look for a weaker person who is less capable of fighting back. Softer targets will be more appealing than someone who seems prepared for violence. Having a firearm openly displayed is like having a loud yappy dog at home. It's not a guaranteed deterrent, but the average crook will pass on you/your home for an easier victim.
#5 - Sometimes the occasion, destination or activity dictates what makes more sense. I'd rather open carry camping or on a long (mainland) road trip. More comfortable, easier to get at, and not visible while inside the vehicle. I can throw a jacket or vest on if I wish to conceal temporarily getting gas or stopping to eat. Going to a nice, dressy event such as a dinner party, concealed would be more appropriate. My choice -- not the legislature's.
#6 - As for the ability to carry rifles openly for self defense, I'm personally against it for myself. Unless it's in a rifle case or scabbard of some sort, it's different than having a holstered handgun. To me, someone with hands on a weapon makes me less comfortable than someone carrying one in a holster. A sling is not the same as a holster. You still have to handle the weapon to sling it on you, adjust it or remove it for sitting. If you have to remove it, you just lost one of the OBVIOUS benefits of wearing a firearm -- constant control.
Nothing OBVIOUSLY bad about carrying a rifle slung on your back. Just more opportunity for someone to accidentally discharge the rifle as they transition from walking to sitting to standing, etc. (IMHO). if we are looking to minimize risks, we have to reduce any potential risks we may present to those around us. Reducing risks is what prompts us to carry in the first place -- risks posed by bad/mentally ill people.
The idea that one-size-fits-all is dangerous. People can decide for themselves. Options are a good thing -- OBVIOUSLY.