BTW, this is like asking why some developers release only Windows or Mac products - they have limited resources and limited income. Add to this that developing for more than one plugin API may require some compromises, and means longer learning curve, longer development and testing cycle. These might be good reasons why some new developers release only CLAP versions (and why some old guys release only VST, and no AU, AAX or LV2). And why @brad does not have time to add CLAP yet.
However, CLAP can make technical sense, especially for modulation and meta plugins.
While I do not use midi controller (I am more into acoustic music than heavy synths and digital effects), CLAP offers not only performance improvements, but also some options not supported in VST3 AFAIK, that might be of interest to Cantabile users based on what I read in this forum:
- per-note automation and modulation (from MIDI 2.0 specification);
- non-destructive parameter modulation with temporary parameter offsets. When the modulation has finished, the target parameter can return to its original state. As I understand, this is more than Reaper or MegaMod can offer;
- polyphonic plug-ins can have their per-voice parameters modulated for individual notes - step up from MIDI Polyphonic Expressions (MPE).
Of course we should still remember that an arbitrary CLAP plugin or host would not necessarily offer the real CLAP advantages, like the more effective, if implemented properly, shared thread pool architecture. It might be just no different from a VST3 plugin/host, but in a different wrap.
And while VST3 became free and open-source (because of pressure from CLAP, BTW), it is still fully controlled by Steinberg with all its legal BS. Independent developers can directly influence the CLAP future development because of its decentralized governance model, and do not need to worry about any legal headaches.