it doesn't do the reputation of the music any good

When did you ever see "knows all their material by heart" as a selling point on a concert flyer?

To most of the potential audience it's irrelevant.

I think the only time I've ever seen the issue come up in a concert review was in a Time magazine review of Jacob Lateiner doing the premiere of Elliott Carter's Piano Concerto - he used a score even after rehearsing it to the exclusion of any other music for six months. The reviewer's comment was along the lines of "as well he might", even though this is unusual for a concerto soloist - he didn't fault Lateiner at all.