There's an idea floating around that it is safest for street riders to only use half of their lane, the right half. 

Specifically we're talking about right hand corners we can't see around. Lefts too, but much more so rights - well, at least the US crowd is.

So, I approach a right hand corner, at what I believe to be a safe speed. I set up near the double yellow to maximize my line of sight. I plan my arc based on paint line arcs, tree line, other visual inputs, and just plain guessing. My arc will take me from the double yellow to the white line. I pick a turn point and flick the bike in.

As I flick the bike in, I spot a pickup truck coming the other way in my lane. As I'm already turning in, I turn in a little tighter and avoid him.

Now the issue being stated here is that my choice of lane position puts me in danger of being hit by that truck. That's simply not the case.

The only thing that would put me in danger of hitting that truck is riding too fast for the available sight distance - the amount of space between when I first see something and when I get to it.

On entry to a corner, the arc of an on coming car is naturally divergent with the arc of the motorcycle. On the exit of a corner, the path of the motorcycle is naturally convergent to the path oncoming car. The danger is not entering the corner but exiting the corner.

With a wide entry it's easier and safer to adjust your exit position than when using a low entry. In general a wide entry is safer and better for the overall performance of the motorcycle - performance that only matters on the track or in emgergencies.

The exit of the corner is what you can't see. Yet using a tight entry will limit your line of sight - reducing available reaction time, require a longer steering inputs - reducing traction, destabilizing the bike, and make your exit wider - putting you directly in the path of the danger you can't see.

On coming vehicle in your lane impact:
at corner entry = riding too fast for sight distance
at apex (white line) = screwed all around
at exit = exiting the corner too wide and riding too fast for sight distance.

I have read one good reason for using a tight entry to a corner and it was combined with a tight exit strategy too. That was from Reg Pridmore describing riding on very narrow roads in either Sweeden or Switzerland. To me, that's just being smart about the environment you're riding in and not a rule that applies everywhere.