Sub Category Issue

A (chord) plugin has a "Instrument|Generator " sub category.
It has MIDI input and MIDI output and Audio Output, but no Audio Input. In this plugin the more important output is the MIDI output. The audio output only seems to be there for a test tone.

Another (Synthesizer) plugin has “Instrument|Synth” sub category with the same MIDI/Audio in/outputs as the one mentioned above. This second one is a synthesizer. There the Audio output seems to be the more important one.

A third (Sequencer) plugin also has “Instrument|Synth” sub category with exact the same in/outputs, but its a Sequencer, where the more important output is the MIDI output.

How to properly distinguish these cases?
Is there a general rule for this?

I implemented a plugin-based “MIDI Out” / “No MIDI Out” menu item in my own VST host, but is this really the only solution possible?
Also the default setting for that switch would be nice to have according to the type of plugin:

  • on a sequencer: default: “MIDI Out”
  • on a synthesizer: default “No MIDI Out”
  • on a chord plugin: default: “MIDI Out”