Yeah I get you. I had that happen too where I'd be flying around, hear the sound and wonder "where the f*** is it though?" and other times I'd just happen upon a shiny without the audio cue.
And I definitely see the benefits but the way I see it, the amount of time I have to spend in raids to get bottle caps, mints, ability caps, etc. is about the same amount of time if not less than it would take to hatch the right egg. I definitely see the value of perfection or near perfection coming right out of the box, but it's a real test on my patience. That said though, I love shiny Charizard so I'm definitely going to masuda one after I clear the 7* raid.