Gimmicky stagecraft?

Is classical-music stagecraft inherently gimmicky? This reviewer seems to think so:

Next came R. Murray Schafer's 1981 String Quartet no. 3. Schafer is one of the most distinguished quartet writers of our time, though one of the quirkiest as well. The majority of his quartets have gimmicks of one sort or another. The Third, for example, begins with the cello alone on the stage, soon to be joined by the other three instruments, each doing its own thing without much regard for the others.

But on the other hand, maybe this sort of thing is better understood as "post-classical" than "classical."

There's an element of theater in any live performance. It's definitely there in a standard formal classical concert, with the dress of the performers, the placement of musicians on the stage, the lighting, the entrances and bows, etc. And the gyrations of the players, or the conspicuous absence of body movement . . . there's always a theatrical element. The standard concert ritual is so familiar that we become blind to it. Some pieces, some performers, purposely challenge the standard ritual by embracing the theatrical element more overtly.