Mglof
You may be French, but you don't know that bit of Paris' suburbs, evidement!
Go back to p.3 of this thread and look at the satellite photo. Draw a line from point 6 to Le Bourget's runway threshold and tell me again that
"the land between CDG and Le Bourget have sadly not more than 100 M maxi of field without big houses, and the highway is a highly used road with a car every 30m or so..." the small fields may be separated by small hedges, but aren't crossed by a serious obstacle until you reach road until nearly Le Bourget's perimeter. Not perfect (but nothing would ever be for a forced landing in Concorde) but eminently survivable for a high proportion of those on board - and less dangerous for those on board and those on the ground than 'spinning in' perilously close to a built up area.