Why didn't they take more photos? Maybe one from the other side, with the sun in the back?
It wasn't like the RAF Tornado pilot had a big time window to take shots from multiple angles, considering the fuel it burned to reach FL600, fly at Mach 2+, align with the Concorde, and leaving enough fuel to return to base. They may have taken more shots from this angle but I guess this was the best one.
Bingo! Obviously the PR value of such a shot is incredible but to be realistic, an air-to-air shot of Concorde at a lower altitude and a subsonic speed is going to look 99% identical in the eyes of people who aren't familiar with how a supersonic shot does or should look, and considering that other than another Concorde the only aircraft that could get such a supersonic shot were (and still are) military types I'm not surprised such shots are scarce...
Indeed it could well even be the case that this particular encounter wasn't even formally arranged but was rather a major case of right-place-right-time for the RAF officer who'd brought his camera along for a lark!
It does make one wander (and yes there are countless threads on how fickle the mx on Concorde was) if Airbus would had done a low level NEO on her with non afterburner supersonic cruise engines, how much less fuel would it had consumed.
Considering that Airbus were actively unwilling to continuing supporting Concorde discussion along these lines is beyond hypothetical, especially seeing as there's some evidence
to suggest that AF were totally committed to their withdrawal from service and therefore colluded with Airbus to prevent BA carrying on as sole operator.
However, your wonderment was addressed in part long before Airbus even came to exist in the way we know today as Aerospatiale began considering such an effort barely four months after EIS in 1976, with the aim of delivering a "B-type" Concorde by late 1982 and laying the groundwork for a hypothetical replacement type for EIS in the mid-'90s.
Concorde B would have used improved-performance versions of the "CEO" engines and also incorporated aerodynamic improvements, changes to certain construction methods and materials, and additional fuel tanks, which would have yielded specs along these lines (assuming a payload of 11260 kg):
Operating Empty Weight (t): 84.3 (+6.3; 8.1%)
Zero Fuel Weight (t): 97.5 (+5.5; 6.0%)
Max Fuel Load (kg): 99790 (+4536; 4.8%)
Max. Landing Weight (t): 115.6 (+4.6; 4.1%)
Max. Take-off Weight (t): 185.9 (+4.5; 2.5%)
Fuel Consumption (kg): 77.9 (-1.2; 1.5%)
Range (km): 6564.5 (+626; 10.5%)
Take-off Noise (EPN dB): 109 (-10.5; 8.8%)
Landing Noise (EPN dB): 109 (-7.7; 6.6%)