[Arran]

I don't think it has as much to do with the size of people's houses, if anything the average house in North America is substantially larger then it was 40 years ago. I think it has to do with nostalgia, the generations of people whom had a sentimental connection with 1920s and 30s radios are either in nursing homes or long gone. When you figure that the average WW2 vet is in his 90s, and Korean war vet in his 80s, it explains a lot. The same story goes with gramophones, telephones, furniture, and mechanical clocks. I saw someone trying to get $350 each from some 1940s and 50s floor lamps on Craigslist, they won't get it, the last floor lamp I got I paid nothing for, and there were no others cued up to get it.
  Late 1920s, early 30s AC radios, and even battery ones, have their own problems inside the one I just mentioned, they only cover up to 1500 kc, as a rule, they are usually TRF (though they should not be condemned for that) and many are difficult to work on compared to a later radio because of the design. One favorite trick from then was to put most of the bypass capacitors in a tar filled can, some put the filter capacitors (paper ones) in the same, I.E the Philco model 86, or an RCA Radiola 18. There is also the problems many have due to age, Majestic and Atwater Kents used miles of rubber/gutta percha wire in certain years, and even cloth wiring that old can be rotted and need replacement.
 Quite often these sets will have failed audio interstage transformers, and or audio output transformers, those can get expensive, there is a solid state substitute for the prior, if it's a class A push pull, but not the audio output transformer. There are some whom are brave enough to rewind these transformers, I have never tried, RF transformers are another matter and the large ones found in older AC sets can often be rewound by hand.
Regards
Arran