If they really were so good, so superior? then we'd all be flying them by now to the top of Everest
You can blame modern certification complexity for an entirely new aircraft type, combined with the cost of something for a market (civil) where additional speed is not typically the main driver for profitable operations.
Otherwise, we would also be witness to a plethora of supersonic commercial airliners...don't you remember those promises in the 1980s as well?