I would like to think chess is art. But what I may like has nothing to do with it.
Consider this...think of the best chess engine...Rybka? Houdini? Fritz? Something else? Well, the frickin' box at highest level can beat the pants off anyone I can think of.
I rest my case.
Calculators that solve math problems have less error than chess engines and yet even in mathematics certain solutions are seen are more elegant and certainly more creative than others.
What is art/creativity and does it exist outside of the human experience is more of a philosophical question... what I mean is by using your type of argument you could reduce anything to cold hard numbers.
Just to throw it out there, computers are effective because programmers work to make their blunder rate approach zero, not because the moves are objectively best. Humans have better ideas (find better moves), but their blunder rate is too high to win in match play.
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The many creative ways you can transform advantageous e.g. give up structure advantage for a superior minor piece are more like art.
The way to convert advantages to wins, i.e. technique, is more science.
The fun is they often blend together seamlessly in a good game. Combined with the nearly inexhaustible number of positions and you get a game that sticks around for over a thousand years.