theres a fair bit of rosy-tinted unreality glass-viewing going on here.
The Nimrod fleet were hit with a double whammy
1) that Coroner's report which condemned the existing fleet as being un-airworthy - and questioned whether they had ever been. The Government & MOD were forced by that into closing down the MR2 fleet before they were ht with further crashes and legal claims. After a suitable time to make it look like the decision was not related to the report, they got rid of the potential liability
2) the MRA4 was never going to work. You had an ancient airframe which had been blacksmithed together with massive individual variation making standardisation of parts impossible, major delay in development which meant the sensor and processing electronics fit would have been ten years out of date by the time it came into service - and with the same inherent problem as with the AEW3 - not enough space in the airframe to cool the electronics / avionics. If the AEW3 couldn't be made to work, there was no way the MRA4 could. It was totally naive to try.
The fault in all this saga lies with firstly BAE for proposing yet again an impossible project, and secondly with the incompetents in the MOD who actually decided it was the best deal. The AEW3 fiasco should have taught them better. What should have been done was to take a widebody airliner and fit the proposed MRA4 electronics into it.
All the Governments did (between both of them) was shoot a pair of dead ducks