People seem to be missing the point. What those of us who are 'defending' committing to an airfield are NOT doing is championing only taking enough fuel to have no diversion available on arrival.
Take an aircraft that arrives at LAM with fuel to hold for 30 minutes, and still have fuel for an approach, lo level go around and diversion to LGW. This, in the assessment of some posters is very sensible airmanship into LHR. After 30 minutes ATC tell him that his approach will start in 10 minutes.
He has 2 choices
1) He diverts to LGW, and is thus effectively committed to landing there as he will not arrive with sufficient fuel to go anywhere else if someone closes the runway.
2) He uses the fuel he would have burnt getting to LGW to stay in the hold for LHR for 10 minutes more, and is thus effectively committed to landing there as he will not arrive with sufficient fuel to go anywhere else if someone closes the runway.
How on earth can 1) be "sensible" and 2) be "stupid" as they are exactly the same (except of course that No.2 has already been briefed, prepared for etc etc and in this case safer as there are 2 runways there).
It is impossible to carry enough fuel to always keep an alternate at all times. Period. Knee jerk reactions in the stylee of the Daily Mail "Shock as Passenger jet had no choice to but to land on Hounslow school if runway closed" do not further an interesting debate.
So, is it safer to commit to a destination, or commit to an alternate?