Are France happy with that? Does France want to attract and house great camps of people destined for another country? What about people who know they will fail in applications(which many of those who arrive do) then carry on and travel across the UK anyway? What do we do with those people? Do we fly them back? Or is that France's job?
I'm not saying any system is perfect, but the current one is repulsive (abused, costly, deadly, enriches criminal gangs, relies on being rich enough to afford the boats etc) and the proposal you advocate has not happened probably for it's own good reasons.
I think a bit of a deterrent is no bad thing. Lots of these people are totally abusing a system designed to help the most vulnerable and that isn't okay.
Worth giving it a trial I think.