I'm not sure why a BBC person would be expected to account for the quality of non BBC stations, but the main BBC ones sound rather better than medium wave, IMHO. And the lack of multi-path reception problems that spoil good FM reception for many are most worthwhile. I only use it for R3&4 reception, and on the whole I'm pleased with it. But a cheaper way for decent domestic reception as an alternative to FM is a secondhand Freeview box - the bitrate on this is higher than DAB, although the choice of stations not so great.
I'm afraid it's those that wanted the high quality that it is capable of that are the reason for the cramming in of lower bandwidth stations - they didn't buy it early enough, so the powers that be decided they needed more choice rather than the ultimate audio quality.