What you say about bomb disposal is quite correct. The fact is of course that that there were quite literally hundreds of men on bomb disposal work throughout WW2, dealing with thousands of bombs, hence the apparent imbalance between wartime and post war awards. The two most recent awards of the George Cross, those to Staff Sergeants Kim Hughes and Olaf Schmidt, RLC (the latter posthumous) were for bomb disposal work in Afghanistan.
I think if we are going to award our gallantry medals very sparingly, as we do, then I think we have to accept the fact that many deserving people will miss out. I think Danny has got it right on the Carol Vorderman thread when he says "when everyone's somebody, nobody's anybody".