Center-left meter bias: how come?

[squirrel$$$bandit]

I was reading Rich Cutler's site on the R-D1 and was surprised to find that here:

http://www.richcutler.co.uk/r-d1/r-d1_03.htm

He says that the light meter is biased toward the center left, same as on the Bessas.

What's the logic here? I can see making the sensitivity biased toward the bottom of the frame, since most light sources are above--presumably this could increase shadow detail. But why left?

 

[squirrel$$$bandit]

For vertical shots, most people using the "right hand up" method.

Ahhh I see...I tend to use left hand up, so that, if I'm wearing a hat with a brim, I don't have to push it back to take the shot. I would have thought this was the more common method...