I'd guess it more has to do with physical colo/datacenter layouts. Traffic moving between racks is considered east/west*. Traffic moving in and out of your routers (and through to the meet-me-room) would take place over fiber pairs up into the ceiling or down through the floor.
Apparently this has nothing to do with getting sun in your eyes.
http://stupidquestionarchives.blogspot.com/2008/03/football-...