Why not...?
After the Paris air crash, AF & BA spent money on updating the entire concorde fleet to such an extent that after they were restored, they were technically brand new aircraft.
Alas, they were taken out of service purely because of finances. Less people were flying with concorde, (one little crash, and in circumstances which could have occured to any aircraft).
Although when both airlines announced they were to get shot of concorde, sales went through the roof, however both airlines were too proud to go back on their word, (and their wallets).
This is why only so few were made, they were very expensive to operate. They also didn't carry many passengers, to each flight was going to cost a lot.
The other reason was that AF and BA were the only airlines which could both afford the aircraft, and have a need to run it (for TA travel). Other EU Airlines couldn't afford to run concordes, or had no need. If they could fly over the land, then more american airlines would probably have bought a few for the NY-LA Run, but as supersonic travel was banned (even opposed by Charles Lyndburg) over the US, they thought it wouldn't be worth it.
If more had been made, more people would have felt comfortable flying on it, and it wouldn't have been taken out of service after just one major incident.