The reality is that they are speakers which were designed by the BBC to act as 'near field studio monitors', with... I believe.. particular attention the reproduction of the human voice. They were designed to be used in cramped studios, in order to let broadcasters hear what was 'going out'.. as it were. They are not full range, they do not have big power handling and they are not very sensitive.. but in the right setting.. they are excellent.
Agreed. They were designed 50 years ago and in the design spec. unsuitability for listening to music was explicitly stated:
"There is a need to monitor sound programme quality in circumstances where space is at a premium and where headphones are not considered satisfactory. Such circumstances include the production-control section of a television mobile control-room, where the producer responsible for the overall production of the programme needs to monitor the output from the sound mixer but at levels lower than those used for mixing."
50 years later speakers with a better technical performance from Genelec, Neumann, and the like are generally used for this task. The fact that people today pay ridiculous sums of money for them given what they are certainly supports a case that they are excellent at something although it doesn't seem to be the original job they were designed for or as high fidelity main speakers for listening to music.