I'm sure there are good solid commercial reasons for doing this, but it is not really conducive to be taken seriously as an artist, is it? I can't help but contrast this with the approach Hilary Hahn takes to her career. She is always doing serious projects and taking her responsibilities as an artist to heart. This, along with her remarkable gifts, is what makes her a cultural treasure. Some other artists seem to regard their dexterity and virtuosity as a path to the fruits of celebrity: big fees, endorsements and notoriety.
Some other things Lang Lang has been up to that make you question his artistic character. Here he is playing with Metallica:
Here he is with a dubstep dancer:
Here he is doing the end of the third movement of the Piano Concerto No. 3 by Prokofiev, with a drummer:
In contrast to the Hahn project, none of these endeavors have a particularly musical purpose. They are really just efforts in promoting celebrity. More people will hear about Lang Lang who are not primarily listeners to classical music.
You know, I don't think that this is the sign of the apocalypse or anything. This has been a strategy for some performers for a long time. It works, it builds audiences but at the same time it reduces the aesthetic authority of the music. Instead of putting yourself at the service of the music, you make the music serve your career goals. But I don't think it fools the more attentive listeners.
Let's hear another kind of pianist. This is Friedrich Gulda doing his variations on "Light My Fire" by the Doors.
Gulda was a somewhat eccentric figure who might be mistaken for the celebrity-seeking kind of artist. But he really wasn't. You notice that what he is doing in the clip is absorbing the rock music of the 60s into a more classical idiom (with a little jazz as well). He is not taking classical music and making it sound like pop music!
Here is Gulda playing the first movement of a Beethoven sonata: