Having spent a bit more time with Vuo's audio tools, I see some real potential. This is a two-part feature request in the spirit of "more better audio".
First request: take a second look at how Vuo manages computer resources regarding audio. For example, dropping frames in video can go unnoticed, whereas when audio hits the limit with distortion, drop-outs, etc., it is immediately disruptive. Right now Vuo feels a little fragile/volatile when pushing these limits. (There is also no current way to monitor when Vuo is getting close to resource limits).
Is there a way to optimize resource management to stabilize audio? Could Vuo, for example, take better advantage of multicore processing for audio (and perhaps even get better performance with audio + visuals)? (To be fair, my experiments have been with Vuo's audio synthesis tools -- these by nature are more resource heavy for real-time processing. Audio-file or sample-based approaches would perform better.)
Audio Units? I don't know if this would even be possible -- what about internal access to Apple's built-in audio units? That would cover a lot of ground with the basics. Do these translate at all to Vuo? Audio units of course would open the door to MIDI instruments, but that really takes it another direction, and the issues with resource management become even more important. But it would be cool.
If not, I'd vote for a couple built-in basic audio effects:
Spatial tools -- Reverb and delay. First choice. Besides making musical sounds more pleasing, consider interactivity -- for example, in game engines like Unreal Engine or Unity one can assign reverb to some sound element to make it seem far or close.
Second on the list of priorities, more EQ (filtering) and tools for dynamics (compressor/limiter).
More -- saturation/distortion, chorus/flanger/phaser.