There's an argument to be made that a continuous function is better than a piecewise function when coming at things mathematically, so in that sense it's at least somewhat interesting.

Sure, in computer science where discrete mathematics is king and the modulus operator is ubiquitous, a cosine representation is entirely unnecessary, but from a recreational mathematical angle, it's a fun distraction.

And it's not like cosine interpolations are useless in a broader sense. They've contributed much to computer graphics.