I'm not sure it's ever been claimed to be totally random. Clubs can make requests for specific games, which is why the last one at Upton Park was against United. I suspect Brighton put in a request for one of the big sides as their first home game this season, hence getting City. The scheduling of long trips for midweek rather than weekends makes some logical sense in a way. Harsh on those who go anyway to say the least, but if the intent is to maximise the crowds then what they do is obvious.