Thursday night I saw Clark Terry perform on campus with his combo. It's been fifteen years since I saw the trumpet king live. While his voice isn't as strong, and he played the entire set sitting in a raised chair, he still can blow that horn. The combo had great time, be it ballad, swing, or samba. It struck me that in many (most?) musical genres, it is rhythm that makes or breaks the performance. Being slightly out of tune is not nearly as noticeable as being out of synchrony. And when a group really hits the groove, that's when the music swings. I'm not talking merely about jazz and popular music here. The same holds true with Baroque, Classical, Romantic, and Contemporary art music. The delightful stretching of tempo created by rubato won't work if the groove isn't set. The harmonic rhythm can't be felt if the portrayal of meter isn't confident and obvious. Greg Sandow wrote about Brahms' practice of making extreme changes of dynamics and tempo "so the audience could more easily follow the shape and flow of the music." This was especially true of unfamiliar pieces to the public, but in today's musically illiterate society, I think it is necessary with most performances. I know that as a performer I delight in making subtle shifts in timbre, pitch, dynamics, and duration. But if the shifts are too slight for the audience to perceive, I might as well play it straight. I think exaggerated portrayal of meter is necessary for the groove to be felt by the audience, otherwise it comes off as uninspired.
Update: John of the perfect cheloniad comments on this post. He has a point that sometimes subtlety is still worthwhile, even if it is at the subconscious level.