I think the title is misleading. It says "When you ABSOLUTELY have to open carry". With the exception of when you've come back from the range, a day of hunting, etc... and you HAVE TO stop off at a Mini-Mart or similar and don't want to leave the weapon in the trunk or otherwise locked up in the car, I don't think you EVER HAVE TO carry open. So, the title doesn't really apply, because you don't ever really HAVE TO carry open. Now, if you don't happen to have a concealed permit, then get one. If where you live won't allow a concealed permit, then chances are they probably discourage or don't allow open carry. But there's a lot of generalization here.
Where I live, open carry is totally legal. And for most locals, it's not a problem; not intimidating; etc... However, we get a lot of "tourists". (Or terrorists; depending on how you look at it). They can become quite intimidated if they see someone walking around with a gun on. Not that it's illegal; it's not. Just that we don't want to freak out the tourist from California, New Jersey, etc...
As for a bad guy seeing the gun, that's actually a positive for open carry. You don't give up any advantage to a bad guy seeing you with a gun. On the contrary. If they see the gun, they will 100% of the time not confront you. And I'll stick by that percentage as basic human psychology unless someone can show actual data that shows a bad guy will actually use the knowledge of someone open carrying a weapon to THEIR advantage.
But again; there's a lot of people who may WANT to open carry. Some may even find it convenient to open carry. But I don't think that except for a very few instances of convenience that anyone HAS TO OPEN CARRY.