Geography starts playing a role when all other roles have been played off and it becomes impossible to defend some area militarily. But GB proved that it can defend it. If they couldn't they would likely try to save the face by pretending that the Falklands are too far from the motherland and they are not worth a penny. Right now it is Argentina who is in a position like this. Really, what prevents them from taking these wretched islands with force if they are so close while Britain is so far?
It seems to me that at this point of time Argentina is not that interested in forcibly asserting its sovereignty over the Falkland Islands. The Argentine economy is not doing that great. But there is another important factor as well. The military strength of the UK is going down with every passing year. The Argentines may be waiting for the UK to become really weak, before they could wage a war against them.