S.F.L.Y
You say that the actions that you propose would increase the glide distance. But what if you had done that, but not quite made it to the runway. The gear would have been damaged by the soft earth, possibly causing a fuel leak. However, because of your longer glide, the aircraft would be travelling much faster when it reached the concrete, with the possibility of sparks igniting the fuel.
The actions that the BA038 crew took resulted in everybody walking away. Can you be certain that your proposed actions would have achieved that?
Dave