The quality of FM
Many years ago, when hi-fi systems were more of a novelty than they are today, FM radio was the highest available quality sound source. Not by measurement, but by listening. With a reasonable system, you could listen to Radio 3, and tell the difference between a live broadcast a record being played. BBC recordings were better than records, and much harder to distinguish from live concerts.
Not much has changed, except that LPs have been replaced by CDs and hi-fi systems are now commonplace and relatively cheap. You don't need anything too exotic to experience excellent sound from FM radio. Especially if you have a good aerial.
Of course, tastes differ, but sound quality affects all kinds of music, and also has considerable impact on speech. Quality especially affects drama, and many people continue to enjoy radio drama.
Why on earth should we be expected to give up on this fine quality for a half baked digital scheme? When digital radio can deliver at least the same quality as FM, that will be the time to consider starting a changeover.