Ever been to Manila, Phillipines? I've spent quite a bit of time there. Despite it having a really bad reputation for scammers, muggers, kidnappings, earthquakes, floods, and typhoons, and even communist seperatists and islamic terrorists I've never had a real problem there worse than a cabbie or street vendor trying to rip me off. You could conclude from my experience that Manila's reputation is undeserved, that it's not actually dangerous, and that fear mongerers who don't know any better have misrepresented it - which is exactly what the OP is arguing about open.
The fact is that Manila IS a dangerous place, there's areas where if you walk in you stand a good chance of being carried out in a bag (if at all). If you're not sensible and too trusting you CAN just disappear, you WILL get mugged, and you WILL have a generally bad day.
Similarly open IS the only place (barring incursions) you will get unwanted pvp attention or that you'll get griefed. No there's not a griefer hiding behind every nav beacon, noone (other than those critisising non-open players) ever claimed that, but there ARE griefers, there IS unwanted pvp, these are NOT required gameplay, and if you don't enjoy them you SHOULD be elsewhere.