If you do it with Melodyne, you first hum something in, then analyse it, then find if it worked as expected, rinse and repeat.
When I tried out Midi Bass, which is also realtime, it became part of the instrument and it's tone. I could try different things on the bass and directly hear what happened, how it reacted, similar to like if you use stomp boxes.
Doing that with Melodyne in a second step would definitely not inspire me, as cool as it may be for more technical things.
Immediate feedback, an instrument in it's own, playing something with the voice. I think that is what people find inspiring here. The cello video did it for me.
Cheers,
Tom
