I'm not dismissing the suggestion but I wanted to point out a some potential issues;
a) upside down maintains system constants like height and width of the display, a 1/4 turn would swap them so they would no longer be 'constants'
b) on some, if not all the players, the upside down seting is done by just setting a flag in the LCD controller
c) the way images are stored and managed internally is (was last time I looked) optimised for efficient transfer to the display - a 1/4 turn may upset this
It's a nice idea but may be a HUGE piece of work...