Yes sin^2 seems to be useless.
All the sin variant are not great and take some memory. I only keep them for preset compatibility since the first versions of the preenfm1.
But now you have user waveforms.... 
Yeah, it definitely needs to stay for compatibility. I just remembered that someone told me that sin^2 had a different spectrum and I believed it until more recently when I'd learned enough about these things to realise it wasn't true.
It does have a use though, it allows a wider ratio range so if you want a wide space between modulator and carrier, this allows for an extra octave.
