Because the substantial technical superiority of CD as a medium was most apparent with wide-dynamic-range, wide-bandwidth orchestral recordings, and of course the recorded sound of real acoustic instruments is easily compared with real life to show up the lack of colouration and noise. As you've pointed out, the classical market is particularly fussy WRT accuracy of recorded sound, and as a consequence CD absolutely obliterated vinyl in the classical sector pretty much overnight - there's been virtually no new classical released on vinyl since the 80s AFAIK. You can trace vinyl's very rapid sink without trace in the title of the Penguin Guide to recommended classical recordings: in 1975 we had the Penguin Stereo Record Guide, which by 1985 was dealing with Records, Cassettes and Compact Discs and by 1988 was down to only Compact Discs and Cassettes.

Karajan famously announced "Everything else is gaslight" during his involvement with the earliest commercial CD recordings, and the classical record-buying public was very quick to agree with him.