The ground up versus ground down discussion is one of those recurring themes that will never be resolved. I see good arguments for both sides, and am firmly of the camp that ground up or down should be left as a choice of the customer, with the freedom to orient receptacles as suits the particulars of the location. I do not want to try to debate this particular issue, but would rather discuss a related approach that would make the issue moot.
Rather that orienting receptacles so that the ground pin would provide some minimal protection from falling objects, why not require partially insulated pins, such as are used in the UK and which are going to be required next year in Australia.
See http://www.tcaust.com/tcaweb/tcapublishing.nsf/Content/18%2F12%2F01+New+Plug+Standard+in+Australia
This would offer the benefit of protection from accidental short no matter what the receptacle orientation and no matter which way metal objects fall. On the other hand, it would require a change in what lots of manufacturers do, which is more complex than mandating what electricians do with already manufactured standard components.
Just a passing thought.
-Jon
