Some people don't care sound quality, and some are not well educated to tell the difference.
I am an engineer, so let me put it in this way.
Higher sample and more bits of info need more data storage. What you gain from there? Higher sample rate will have higher bandwidth and therefore make it easier for smooth high frequency sounding. A similar DAC/amp CKT will sound more refined and smooth on SACD format. More bit will give you more dynamic sound. For example, most of music are in the middle loud range, so a CD will give 12 bit (just for example) to record the music to cover enough detail for most of music in moderate loud range. However it leaves only 6 bit for very loud or quiet level. Therefore a CD might lose the resolution or layers when the music comes to very loud or whisper quiet.
In real life, a SONY 775 playing SACD rivals redbook player >$500 (even >1K redbook machine). Why? a higher sampling rate makes DAC/amp CKT easier to achieve high resolution and smooth sound. So 775 may not have a fancy OP or DAC, but still not bad for SACD. A redbook player has to have expensive DAC/amp to sing not be edgy. A expensive redbook can get rid of edgy sound by good DAC/amp design (which SACD can do too), but they will not have the same layers (namely dynamics) as LP/SACD.
For dynamics, did you ever wonder why a pop CD always give you the same punch in the music? Some are from electronic instrument, and some are from the compressed data in CD format. They ain't sound bad acoustically, but just lacks of layers like drummer is repeating his work without emotion. Try to hear a LP or SACD playing symphony, the drum or bass/cello winding low freq. They have loud, Loud+, very loud, damn loud...., suddenly all layers are there, and the music is more exciting. Then you realize that the performers are more creative than you thought hearing in CD. It sound more like a human playing not a robot. The extra bits help SACD to sing more like a analog source.
Of course, some people don't care, they are happy with what they have. Some enjoy VCR as much as DVD, nothing wrong with it. You save $$ if so. But "people don't care" is not "there is no differece".
Some do care and maybe they are willing to buy the products which makes music more expressive.