That is really unfortunate. Was a feature on the Evolver line. Would love to see this implemented somehow.
More options is usually better, of course, and that would be nice. I can see Osc 3 Shape modulation being particularly useful in an instrument with more than one wavetable oscillator, to do cross-fading. But, from a practical standpoint, the Pro 3 already has plenty of resources to do wave sequencing. If you want to control wave shape over time, the Pro 3's voice architecture is way better at that than the original Wavestation's was. It just lacks the polyphony.
But you wouldn't see me complaining if they could add this destination!
Note that Sequential is underselling the capabilities of their wavetable oscillator. A Pro 3 "wavetable" file contains four 16-wave wavetables. In all the preset wavetables, and the wavetables generated by Sequential's tool, all four of these wavetables are the same, at different frequencies. But there's no reason this must be the case. By modulating both pitch and wave shape of multi-dimensional wavetables, it's possible to access 64 different waveforms. (See
https://forum.sequential.com/index.php/topic,4917.0.html)