7's Olympic Qualifying

Basically it's down to this. It's basically the same for womens as well.

"Under the qualification structure for the men’s competition, four nations will qualify from the 2014/15 Sevens World Series, one nation from each of the six IRB regional competitions, one from the world play-off and automatic qualification for Brazil."

For more here's the link.

http://www.irb.com/rugbyandtheolympics/news/newsid=2070257.html#olympic+rugby+sevens+qualification+confirmed

Assuming current standings indicate relative strength the teams would be (as long as I have regions correct):
South Africa  (automatic)
New Zealand  (automatic)Fiji   (automatic)England  (automatic)Kenya (Africa region)Russia / Japan ? (Asia region - weak)France (Europe region)Canada (North America region)Samoa (Oceania region)Argentina  (South America region)Australia (world playoff tournament)Brazil (host nation)
All the big dogs get in, notables left out: Wales, Scotland, USA

I think Russia is European. For Union they play in European nations cup to qualify for RWC's. Also, their football teams play in Champions and Europa leagues....

When I saw the process I knew right away that some really good teams would be left out, while some average teams would make it in.

Kind of takes a little away from it... But like you said, all the top dogs should be there.